:root {
  color-scheme: light;
  --paper: #f7f3ea;
  --paper-deep: #efe8da;
  --surface: #fffdf8;
  --surface-strong: #ffffff;
  --ink: #18313a;
  --ink-soft: #5d7077;
  --ink-faint: #839298;
  --line: #dfe3dc;
  --line-strong: #cbd4cc;
  --blue: #2f6fed;
  --blue-dark: #1e4eae;
  --blue-pale: #eaf1ff;
  --orange: #f28c28;
  --orange-dark: #a94d10;
  --orange-pale: #fff0dc;
  --teal: #0e8a9c;
  --teal-dark: #086271;
  --teal-pale: #e2f5f5;
  --green: #16845b;
  --green-dark: #0c6242;
  --green-pale: #e7f5ed;
  --violet: #7856c8;
  --violet-dark: #533797;
  --violet-pale: #f0ebff;
  --rose: #d25562;
  --yellow: #f8ca57;
  --focus: #145bcc;
  --shadow-soft: 0 12px 32px rgba(45, 62, 61, 0.08);
  --shadow-card: 0 20px 55px rgba(48, 65, 63, 0.11), 0 2px 0 rgba(255, 255, 255, 0.9) inset;
  --radius-sm: 12px;
  --radius-md: 18px;
  --radius-lg: 26px;
  --radius-xl: 34px;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-soft: cubic-bezier(0.25, 0.8, 0.3, 1);
  --accent: var(--blue);
  --accent-dark: var(--blue-dark);
  --accent-pale: var(--blue-pale);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 7% 7%, rgba(248, 202, 87, 0.27) 0 5px, transparent 6px),
    radial-gradient(circle at 93% 14%, rgba(47, 111, 237, 0.16) 0 4px, transparent 5px),
    radial-gradient(circle at 88% 87%, rgba(14, 138, 156, 0.11) 0 6px, transparent 7px),
    linear-gradient(180deg, #faf6ee 0%, #f4f7f1 47%, #f7f2e8 100%);
  font-family: "Avenir Next", "Nunito", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

button,
select {
  font: inherit;
}

button,
a,
select {
  -webkit-tap-highlight-color: transparent;
}

button:focus-visible,
a:focus-visible,
select:focus-visible,
[tabindex]:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--focus) 75%, white);
  outline-offset: 3px;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.48;
}

.skip-link {
  position: fixed;
  z-index: 1000;
  top: 12px;
  left: 12px;
  padding: 10px 16px;
  color: white;
  background: var(--focus);
  border-radius: var(--radius-sm);
  font-weight: 800;
  transform: translateY(-160%);
  transition: transform 180ms ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.sr-live {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.topbar {
  width: min(1380px, calc(100% - 48px));
  min-height: 84px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  border-bottom: 1px solid rgba(24, 49, 58, 0.12);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
}

.brand-mark {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  color: var(--ink);
  background: var(--yellow);
  border: 2px solid var(--ink);
  border-radius: 16px;
  box-shadow: 0 4px 0 rgba(24, 49, 58, 0.18);
  transform: rotate(-3deg);
}

.brand-mark svg {
  width: 34px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.brand-mark circle {
  fill: currentColor;
  stroke: none;
}

.brand-copy {
  display: flex;
  flex-direction: column;
}

.brand-copy strong {
  font-size: 18px;
  font-weight: 900;
  letter-spacing: -0.02em;
}

.brand-copy small {
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 700;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.progress-link {
  min-height: 42px;
  padding: 8px 14px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--ink);
  background: rgba(255, 253, 248, 0.82);
  border: 1px solid rgba(24, 49, 58, 0.14);
  border-radius: 999px;
  box-shadow: 0 5px 14px rgba(45, 62, 61, 0.05);
  font-size: 13px;
  font-weight: 850;
  text-decoration: none;
  transition: transform 280ms var(--ease-out), border-color 280ms ease, background 280ms ease;
}

.progress-link:hover {
  background: white;
  border-color: color-mix(in srgb, var(--teal) 45%, white);
  transform: translateY(-2px);
}

.progress-link svg {
  width: 18px;
  fill: none;
  stroke: var(--teal-dark);
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.topbar-status {
  min-height: 40px;
  padding: 8px 14px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: #365b50;
  background: rgba(255, 255, 255, 0.64);
  border: 1px solid #d9e4dc;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 800;
  backdrop-filter: blur(12px);
}

.status-dot {
  width: 9px;
  height: 9px;
  background: var(--green);
  border: 2px solid white;
  border-radius: 50%;
  box-shadow: 0 0 0 2px rgba(22, 132, 91, 0.18);
}

.page-shell {
  width: min(1380px, calc(100% - 48px));
  margin: 0 auto;
}

.intro {
  padding: 48px 0 30px;
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(280px, 0.65fr);
  align-items: end;
  gap: 48px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--teal-dark);
  font-size: 13px;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.eyebrow span {
  margin-right: 8px;
  color: var(--orange);
}

.intro h1 {
  margin: 0;
  max-width: 820px;
  font-size: clamp(34px, 5vw, 62px);
  line-height: 1.06;
  letter-spacing: -0.055em;
}

.intro h1 span {
  color: var(--blue);
  text-decoration: underline;
  text-decoration-color: rgba(248, 202, 87, 0.78);
  text-decoration-thickness: 0.17em;
  text-underline-offset: -0.08em;
  text-decoration-skip-ink: none;
}

.intro-copy {
  margin: 0 0 7px;
  padding-left: 22px;
  color: var(--ink-soft);
  border-left: 3px solid var(--yellow);
  font-size: 15px;
  font-weight: 650;
}

.runtime-layout {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  align-items: start;
  gap: 22px;
}

.course-panel {
  position: sticky;
  top: 16px;
  padding: 22px;
  background: rgba(255, 253, 248, 0.82);
  border: 1px solid rgba(24, 49, 58, 0.12);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(18px);
}

.panel-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.panel-kicker {
  color: var(--ink-faint);
  font-size: 10px;
  font-weight: 900;
  letter-spacing: 0.12em;
}

.panel-heading h2 {
  margin: 3px 0 0;
  font-size: 18px;
  letter-spacing: -0.025em;
}

.panel-heading-actions {
  display: flex;
  align-items: center;
  gap: 6px;
}

.course-panel-toggle {
  display: none;
}

.course-count {
  padding: 5px 8px;
  color: var(--teal-dark);
  background: var(--teal-pale);
  border-radius: 9px;
  font-size: 11px;
  font-weight: 900;
}

.grade-filter {
  margin-top: 14px;
  padding: 4px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 3px;
  background: rgba(31, 65, 71, 0.06);
  border: 1px solid rgba(31, 65, 71, 0.08);
  border-radius: 13px;
}

.grade-filter button {
  min-height: 44px;
  padding: 5px 3px;
  color: var(--ink-soft);
  background: transparent;
  border: 0;
  border-radius: 10px;
  cursor: pointer;
  font-size: 10px;
  font-weight: 850;
}

.grade-filter button[aria-pressed="true"] {
  color: var(--teal-dark);
  background: white;
  box-shadow: 0 3px 10px rgba(42, 64, 58, 0.1);
}

.course-list {
  margin-top: 18px;
  max-height: min(66vh, 720px);
  padding-right: 4px;
  display: grid;
  gap: 10px;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: color-mix(in srgb, var(--teal) 32%, white) transparent;
}

.course-button {
  width: 100%;
  min-height: 112px;
  padding: 13px;
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr) 24px;
  align-items: center;
  gap: 11px;
  color: var(--ink);
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid #dfe3de;
  border-radius: 18px;
  cursor: pointer;
  text-align: left;
  transition: transform 260ms var(--ease-out), border-color 260ms ease, background 260ms ease, box-shadow 260ms ease;
}

.course-button:hover {
  transform: translateY(-2px);
  background: white;
  border-color: var(--line-strong);
  box-shadow: 0 10px 20px rgba(42, 64, 58, 0.08);
}

.course-button.is-active {
  background: white;
  border-color: var(--course-accent, var(--blue));
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--course-accent, var(--blue)) 11%, transparent), 0 10px 22px rgba(42, 64, 58, 0.09);
}

.course-button--teal { --course-accent: var(--teal); --course-pale: var(--teal-pale); }
.course-button--blue { --course-accent: var(--blue); --course-pale: var(--blue-pale); }
.course-button--violet { --course-accent: var(--violet); --course-pale: var(--violet-pale); }
.course-button--orange { --course-accent: var(--orange); --course-pale: var(--orange-pale); }

.course-icon {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  color: var(--course-accent);
  background: var(--course-pale);
  border: 1px solid color-mix(in srgb, var(--course-accent) 24%, white);
  border-radius: 15px;
  font-size: 17px;
  font-weight: 950;
}

.course-button-copy {
  min-width: 0;
  display: flex;
  flex-direction: column;
}

.course-button-copy small {
  color: var(--course-accent);
  font-size: 10px;
  font-weight: 900;
}

.new-course-tag {
  margin-left: 6px;
  padding: 2px 5px;
  color: white;
  background: var(--course-accent);
  border-radius: 999px;
  font-size: 8px;
  font-style: normal;
  letter-spacing: .04em;
}

.course-button-copy strong {
  margin-top: 3px;
  display: -webkit-box;
  overflow: hidden;
  font-size: 14px;
  font-weight: 900;
  line-height: 1.3;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

.course-button-copy > span {
  margin-top: 4px;
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 700;
}

.course-arrow {
  color: var(--ink-faint);
  font-size: 26px;
}

.complete-mark {
  width: 24px;
  height: 24px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--green);
  border-radius: 50%;
  font-size: 12px;
  font-weight: 900;
}

.course-panel-note {
  margin-top: 16px;
  padding: 13px;
  display: flex;
  gap: 10px;
  color: #5c654e;
  background: #fff7dc;
  border: 1px solid #eadca5;
  border-radius: 15px;
}

.course-panel-note svg {
  width: 22px;
  flex: 0 0 22px;
  fill: none;
  stroke: #9b7415;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.course-panel-note p {
  margin: 0;
  font-size: 11px;
}

.lesson-runtime {
  min-width: 0;
  min-height: 850px;
  overflow: hidden;
  background: var(--surface);
  border: 1px solid rgba(24, 49, 58, 0.12);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card);
}

.lesson-runtime[data-accent="teal"] { --accent: var(--teal); --accent-dark: var(--teal-dark); --accent-pale: var(--teal-pale); }
.lesson-runtime[data-accent="blue"] { --accent: var(--blue); --accent-dark: var(--blue-dark); --accent-pale: var(--blue-pale); }
.lesson-runtime[data-accent="violet"] { --accent: var(--violet); --accent-dark: var(--violet-dark); --accent-pale: var(--violet-pale); }
.lesson-runtime[data-accent="orange"] { --accent: var(--orange); --accent-dark: #9f421b; --accent-pale: var(--orange-pale); }

.loading-state,
.error-state {
  min-height: 720px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 32px;
  text-align: center;
}

.loading-state[hidden],
.error-state[hidden],
.runtime-content[hidden] {
  display: none;
}

.loading-state strong,
.error-state strong {
  margin-top: 18px;
  font-size: 20px;
}

.loading-state small,
.error-state p {
  margin-top: 5px;
  color: var(--ink-soft);
}

.loading-orbit {
  width: 62px;
  height: 62px;
  border: 6px solid var(--blue-pale);
  border-top-color: var(--blue);
  border-radius: 50%;
  animation: spin 1.4s linear infinite;
}

.lesson-header {
  min-height: 138px;
  padding: 25px 30px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  background:
    linear-gradient(105deg, rgba(255,255,255,0.9), rgba(255,255,255,0.48)),
    repeating-linear-gradient(-45deg, transparent 0 14px, color-mix(in srgb, var(--accent) 6%, transparent) 14px 28px),
    var(--accent-pale);
  border-bottom: 1px solid color-mix(in srgb, var(--accent) 18%, white);
}

.lesson-meta {
  display: flex;
  gap: 7px;
}

.grade-chip,
.domain-chip {
  min-height: 26px;
  padding: 4px 9px;
  display: inline-flex;
  align-items: center;
  border-radius: 8px;
  font-size: 10px;
  font-weight: 900;
}

.grade-chip {
  color: white;
  background: var(--accent);
}

.domain-chip {
  color: var(--accent-dark);
  background: rgba(255,255,255,0.72);
  border: 1px solid color-mix(in srgb, var(--accent) 24%, white);
}

.formal-title {
  margin: 9px 0 2px;
  color: var(--accent-dark);
  font-size: 11px;
  font-weight: 850;
  letter-spacing: 0.06em;
}

.lesson-heading h2 {
  margin: 0;
  max-width: 700px;
  font-size: clamp(23px, 3vw, 34px);
  line-height: 1.18;
  letter-spacing: -0.035em;
}

.lesson-progress-wrap {
  width: 190px;
  flex: 0 0 190px;
}

.progress-copy {
  margin-bottom: 7px;
  display: flex;
  justify-content: space-between;
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 800;
}

.progress-copy strong {
  color: var(--accent-dark);
  font-size: 12px;
}

.lesson-progress {
  height: 10px;
  overflow: hidden;
  background: rgba(255,255,255,0.75);
  border: 1px solid color-mix(in srgb, var(--accent) 18%, white);
  border-radius: 999px;
}

.lesson-progress span {
  width: 0;
  height: 100%;
  display: block;
  background: linear-gradient(90deg, var(--accent), color-mix(in srgb, var(--accent) 68%, var(--yellow)));
  border-radius: inherit;
  transition: width 650ms var(--ease-out);
}

.readiness-card {
  margin: 14px 22px 0;
  overflow: hidden;
  background: color-mix(in srgb, var(--accent-pale) 38%, white);
  border: 1px solid color-mix(in srgb, var(--accent) 16%, var(--line));
  border-radius: 18px;
  box-shadow: 0 8px 22px rgba(45, 62, 61, 0.045);
}

.readiness-card[hidden],
.readiness-details[hidden] {
  display: none;
}

.readiness-toggle {
  width: 100%;
  min-height: 64px;
  padding: 10px 14px;
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr) auto 24px;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  background: transparent;
  border: 0;
  cursor: pointer;
  text-align: left;
}

.readiness-toggle:hover {
  background: rgba(255, 255, 255, 0.58);
}

.readiness-icon {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  color: var(--accent-dark);
  background: white;
  border: 1px solid color-mix(in srgb, var(--accent) 24%, white);
  border-radius: 12px;
  font-size: 18px;
  font-weight: 900;
}

.readiness-toggle > span:nth-child(2) {
  display: flex;
  flex-direction: column;
}

.readiness-toggle small {
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 750;
}

.readiness-toggle strong {
  font-size: 14px;
  font-weight: 900;
}

.readiness-state {
  padding: 5px 9px;
  color: var(--accent-dark);
  background: white;
  border: 1px solid color-mix(in srgb, var(--accent) 18%, white);
  border-radius: 999px;
  font-size: 10px;
  font-weight: 850;
  white-space: nowrap;
}

.readiness-state.is-ready {
  color: var(--green-dark);
  background: var(--green-pale);
  border-color: #c6e4d3;
}

.readiness-chevron {
  color: var(--ink-soft);
  font-size: 20px;
  transform: rotate(0);
  transition: transform 360ms var(--ease-out);
}

.readiness-toggle[aria-expanded="true"] .readiness-chevron {
  transform: rotate(180deg);
}

.readiness-details {
  padding: 2px 16px 16px 62px;
  animation: reveal-soft 420ms var(--ease-out) both;
}

.readiness-details > p {
  max-width: 720px;
  margin: 0 0 12px;
  color: var(--ink-soft);
  font-size: 12px;
}

.readiness-details ul {
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
  list-style: none;
}

.readiness-details li {
  min-height: 58px;
  padding: 9px 10px;
  display: grid;
  grid-template-columns: 12px minmax(0, 1fr);
  gap: 5px;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid rgba(24, 49, 58, 0.08);
  border-radius: 12px;
}

.readiness-details li > span:first-child {
  color: var(--accent);
  font-weight: 900;
}

.readiness-details li span:last-child {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.readiness-details li strong {
  font-size: 11px;
  line-height: 1.35;
}

.readiness-details li small {
  color: var(--ink-soft);
  font-size: 9px;
}

.readiness-suggestion {
  margin-top: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.readiness-suggestion > span {
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 800;
}

.readiness-suggestion button {
  min-height: 38px;
  padding: 6px 11px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: white;
  background: var(--accent);
  border: 0;
  border-radius: 10px;
  font-size: 11px;
  font-weight: 850;
  cursor: pointer;
}

@keyframes reveal-soft {
  from { opacity: 0; transform: translateY(-7px); }
  to { opacity: 1; transform: translateY(0); }
}

.scene-nav {
  padding: 16px 22px;
  display: flex;
  gap: 6px;
  overflow-x: auto;
  background: #fbfcf9;
  border-bottom: 1px solid var(--line);
  scrollbar-width: thin;
  scrollbar-color: color-mix(in srgb, var(--accent) 38%, white) transparent;
  scroll-snap-type: x proximity;
  overscroll-behavior-inline: contain;
}

.scene-nav::-webkit-scrollbar {
  height: 6px;
}

.scene-nav::-webkit-scrollbar-track {
  background: transparent;
}

.scene-nav::-webkit-scrollbar-thumb {
  background: color-mix(in srgb, var(--accent) 34%, white);
  border-radius: 999px;
}

.scene-step {
  min-width: 72px;
  min-height: 58px;
  padding: 6px 8px;
  flex: 1 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  color: var(--ink-faint);
  background: transparent;
  border: 1px solid transparent;
  border-radius: 13px;
  cursor: pointer;
  scroll-snap-align: center;
  transition: color 260ms ease, background 260ms ease, transform 260ms var(--ease-out), border-color 260ms ease;
}

.scene-step:hover {
  color: var(--ink);
  background: white;
  border-color: var(--line);
}

.scene-step > span {
  width: 25px;
  height: 25px;
  display: grid;
  place-items: center;
  background: #e9ece8;
  border-radius: 50%;
  font-size: 10px;
  font-weight: 900;
}

.scene-step small {
  font-size: 9px;
  font-weight: 800;
  white-space: nowrap;
}

.scene-step.is-active {
  color: var(--accent-dark);
  background: var(--accent-pale);
  border-color: color-mix(in srgb, var(--accent) 25%, white);
  transform: translateY(-2px);
}

.scene-step.is-active > span {
  color: white;
  background: var(--accent);
}

.scene-step.is-passed > span {
  color: white;
  background: var(--green);
}

.scene-step--practice > span {
  border-radius: 8px;
}

.scene-card {
  padding: 26px 30px 22px;
  background:
    linear-gradient(rgba(24,49,58,0.026) 1px, transparent 1px),
    linear-gradient(90deg, rgba(24,49,58,0.026) 1px, transparent 1px),
    #fffefb;
  background-size: 28px 28px;
}

.scene-copy {
  min-height: 94px;
  display: grid;
  grid-template-columns: 136px minmax(0, 0.8fr) minmax(280px, 1.2fr);
  align-items: center;
  gap: 18px;
}

.phase-badge {
  min-height: 48px;
  padding: 8px 12px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border: 1px solid color-mix(in srgb, var(--accent) 24%, white);
  border-radius: 14px;
  font-size: 13px;
  font-weight: 900;
}

.phase-badge span {
  width: 29px;
  height: 29px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--accent);
  border-radius: 9px;
  font-size: 10px;
}

.scene-purpose {
  margin: 0;
  color: var(--ink-soft);
  font-size: 13px;
  font-weight: 700;
}

.teacher-line {
  min-height: 68px;
  padding: 13px 17px 13px 52px;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 2px;
  background: white;
  border: 1px solid #dbe3df;
  border-radius: 18px;
  box-shadow: 0 5px 0 rgba(44, 64, 59, 0.06);
}

.teacher-line::before {
  content: "想";
  position: absolute;
  left: 10px;
  top: 13px;
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border-radius: 11px;
  font-size: 12px;
  font-weight: 950;
}

.teacher-sentence {
  color: var(--ink-soft);
  font-size: 12px;
  font-weight: 700;
  animation: sentence-in 650ms var(--ease-out) both;
}

.teacher-sentence.is-main {
  color: var(--ink);
  font-size: 15px;
  font-weight: 900;
}

.math-stage {
  min-height: 410px;
  padding: 18px 0;
  display: grid;
  place-items: center;
}

.model-frame {
  position: relative;
  width: min(100%, 880px);
  min-height: 370px;
  padding: 42px 28px 26px;
  display: grid;
  place-items: center;
  background:
    radial-gradient(circle at 12% 18%, color-mix(in srgb, var(--accent) 6%, transparent) 0 80px, transparent 81px),
    linear-gradient(160deg, #ffffff, #fbfcf9);
  border: 1px solid #dfe5df;
  border-radius: 26px;
  box-shadow: 0 14px 34px rgba(47, 66, 61, 0.08), inset 0 1px 0 #fff;
  animation: stage-in 650ms var(--ease-out) both;
}

.model-label {
  position: absolute;
  top: 12px;
  left: 14px;
  padding: 5px 9px;
  display: flex;
  align-items: baseline;
  gap: 6px;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border-radius: 9px;
}

.model-label span {
  font-size: 11px;
  font-weight: 900;
}

.model-label small {
  color: var(--ink-faint);
  font-size: 8px;
  font-weight: 800;
}

.scene-evidence {
  min-height: 62px;
  padding: 10px 15px;
  display: flex;
  align-items: center;
  gap: 12px;
  color: #3f6758;
  background: var(--green-pale);
  border: 1px solid #c8e5d4;
  border-radius: 16px;
}

.scene-evidence > span {
  width: 34px;
  height: 34px;
  flex: 0 0 34px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--green);
  border-radius: 50%;
  font-weight: 900;
}

.scene-evidence p {
  margin: 0;
  display: flex;
  flex-direction: column;
  font-size: 11px;
}

.scene-evidence strong {
  font-size: 10px;
  letter-spacing: 0.05em;
}

.animation-panel {
  min-height: 78px;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  background: #f7faf7;
  border-top: 1px solid var(--line);
}

.animation-panel[hidden] {
  display: none;
}

.animation-status {
  display: grid;
  grid-template-columns: 13px auto;
  align-items: center;
  column-gap: 9px;
}

.animation-status strong {
  font-size: 12px;
}

.animation-status > span:last-child {
  grid-column: 2;
  color: var(--ink-soft);
  font-size: 10px;
}

.animation-pulse {
  width: 10px;
  height: 10px;
  background: var(--accent);
  border-radius: 50%;
  box-shadow: 0 0 0 5px color-mix(in srgb, var(--accent) 12%, transparent);
}

.animation-actions,
.model-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
}

.control-button,
.icon-button,
.math-action,
.math-reset,
.answer-button {
  min-height: 48px;
  border: 1px solid #cfd8d2;
  border-radius: 14px;
  cursor: pointer;
  font-weight: 850;
  transition: transform 180ms var(--ease-out), box-shadow 180ms ease, background 180ms ease, border-color 180ms ease;
  touch-action: manipulation;
}

.control-button:hover:not(:disabled),
.icon-button:hover:not(:disabled),
.math-action:hover:not(:disabled),
.answer-button:hover:not(:disabled) {
  transform: translateY(-2px);
}

.control-button:active:not(:disabled),
.icon-button:active:not(:disabled),
.math-action:active:not(:disabled),
.answer-button:active:not(:disabled) {
  transform: translateY(1px) scale(0.99);
}

.control-button {
  padding: 10px 15px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  color: var(--ink);
  background: white;
}

.control-button svg,
.icon-button svg {
  width: 20px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.control-button--primary,
.control-button--next,
.math-action {
  color: white;
  background: var(--accent);
  border-color: var(--accent-dark);
  box-shadow: 0 4px 0 var(--accent-dark);
}

.control-button--primary:active:not(:disabled),
.control-button--next:active:not(:disabled),
.math-action:active:not(:disabled) {
  box-shadow: 0 1px 0 var(--accent-dark);
}

.control-button--quiet {
  color: var(--ink-soft);
  background: #f7f8f5;
}

.icon-button {
  width: 48px;
  padding: 0;
  display: grid;
  place-items: center;
  color: var(--ink-soft);
  background: white;
}

.speed-control {
  min-height: 48px;
  padding: 5px 7px 5px 11px;
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--ink-soft);
  background: white;
  border: 1px solid #cfd8d2;
  border-radius: 14px;
  font-size: 10px;
  font-weight: 800;
}

.speed-control select {
  min-height: 36px;
  color: var(--ink);
  background: #f3f6f2;
  border: 0;
  border-radius: 9px;
  font-size: 11px;
  font-weight: 800;
}

.runtime-footer {
  min-height: 82px;
  padding: 14px 24px;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 16px;
  background: white;
  border-top: 1px solid var(--line);
}

.footer-note {
  color: var(--ink-faint);
  font-size: 10px;
  font-weight: 700;
  text-align: center;
}

/* Ten frame */
.ten-frame-scene {
  width: 100%;
  display: grid;
  grid-template-columns: 90px minmax(280px, 470px) minmax(150px, 210px);
  align-items: center;
  justify-content: center;
  gap: 22px;
}

.quantity-card {
  padding: 13px 9px;
  display: flex;
  flex-direction: column;
  align-items: center;
  color: var(--blue-dark);
  background: var(--blue-pale);
  border: 1px solid #cddcfa;
  border-radius: 16px;
}

.quantity-card span,
.quantity-card small {
  font-size: 9px;
  font-weight: 800;
}

.quantity-card strong {
  font-size: 30px;
  font-weight: 950;
}

.ten-board {
  padding: 12px;
  display: grid;
  grid-template-columns: repeat(5, minmax(44px, 1fr));
  gap: 7px;
  background: #f5ead1;
  border: 3px solid #9c723a;
  border-radius: 18px;
  box-shadow: inset 0 -7px 0 rgba(119, 76, 29, 0.09), 0 7px 0 rgba(119, 76, 29, 0.11);
}

.ten-cell {
  position: relative;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  background: rgba(255,255,255,0.63);
  border: 2px dashed #c6b593;
  border-radius: 11px;
}

.ten-cell.is-filled {
  border-style: solid;
  border-color: rgba(47,111,237,0.15);
}

.ten-cell.is-new {
  background: var(--orange-pale);
  border-color: rgba(242,140,40,0.32);
}

.empty-index {
  color: #b0a58f;
  font-size: 9px;
  font-weight: 800;
}

.counter {
  width: clamp(28px, 4vw, 42px);
  aspect-ratio: 1;
  display: block;
  border: 2px solid;
  border-radius: 50%;
  box-shadow: inset -4px -5px 0 rgba(0,0,0,0.08), 0 4px 0 rgba(35,57,64,0.12);
  animation: counter-in 950ms var(--ease-out) var(--delay, 0ms) both;
}

.counter--blue {
  background: #5a8df2;
  border-color: var(--blue-dark);
}

.counter--orange {
  background: #f6a34d;
  border-color: var(--orange-dark);
}

.incoming-tray {
  min-height: 138px;
  padding: 15px;
  background: #fff8ec;
  border: 2px solid #efcf9f;
  border-radius: 50% 50% 22px 22px;
  box-shadow: inset 0 -8px 0 #f9e9cb;
}

.tray-title {
  display: block;
  color: var(--orange-dark);
  font-size: 10px;
  font-weight: 800;
  text-align: center;
}

.tray-tokens {
  min-height: 72px;
  margin-top: 10px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 7px;
}

.counter--tray {
  width: 31px;
}

.tray-empty {
  color: var(--ink-faint);
  font-size: 10px;
  font-weight: 800;
}

.outside-result,
.math-result-chip {
  grid-column: 2;
  justify-self: center;
}

.outside-result {
  padding: 8px 12px;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--orange-dark);
  background: var(--orange-pale);
  border-radius: 12px;
  font-size: 10px;
  animation: rise-in 800ms var(--ease-out) both;
}

.outside-result strong {
  font-size: 20px;
}

.math-result-chip {
  padding: 8px 15px;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border: 1px solid color-mix(in srgb, var(--accent) 22%, white);
  border-radius: 13px;
  font-size: 18px;
  font-weight: 850;
}

.ten-frame-scene .model-actions {
  grid-column: 1 / -1;
}

/* Base ten */
.base-ten-scene {
  width: 100%;
  display: grid;
  grid-template-columns: minmax(190px, 1fr) 120px minmax(190px, 1fr);
  align-items: center;
  gap: 20px;
}

.base-group {
  min-height: 220px;
  padding: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: #f9fbf8;
  border: 1px solid #dce4de;
  border-radius: 22px;
}

.base-group--tens {
  background: var(--teal-pale);
  border-color: #b9dddd;
}

.base-label {
  min-width: 38px;
  padding: 4px 8px;
  color: white;
  background: var(--teal);
  border-radius: 8px;
  font-size: 11px;
  font-weight: 900;
  text-align: center;
}

.base-group--ones .base-label {
  background: var(--blue);
}

.rod-list,
.cube-list {
  min-height: 130px;
  margin: 12px 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 8px;
}

.ten-rod {
  width: 34px;
  height: 128px;
  padding: 2px;
  display: grid;
  grid-template-rows: repeat(10, 1fr);
  background: #2f9dac;
  border: 2px solid var(--teal-dark);
  border-radius: 7px;
  box-shadow: 0 5px 0 rgba(8,98,113,0.18);
  animation: rod-in 1200ms var(--ease-out) var(--delay, 0ms) both;
}

.ten-rod span {
  border-bottom: 1px solid rgba(255,255,255,0.52);
}

.one-cube,
.mini-one {
  width: 31px;
  aspect-ratio: 1;
  display: block;
  background: #5c8ff3;
  border: 2px solid var(--blue-dark);
  border-radius: 7px;
  box-shadow: inset -3px -3px 0 rgba(25,66,154,0.13), 0 3px 0 rgba(30,78,174,0.15);
  animation: cube-in 900ms var(--ease-out) var(--delay, 0ms) both;
}

.empty-unit {
  color: var(--ink-faint);
  font-size: 10px;
  font-style: normal;
  font-weight: 750;
}

.base-group > strong {
  font-size: 14px;
}

.exchange-arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  color: var(--ink-soft);
}

.exchange-arrow b {
  color: var(--accent);
  font-size: 36px;
}

.exchange-arrow span {
  font-size: 10px;
  font-weight: 850;
}

.quantity-conservation {
  grid-column: 1 / -1;
  justify-self: center;
  padding: 8px 14px;
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--green-pale);
  border: 1px solid #c5e3d1;
  border-radius: 12px;
  font-size: 10px;
}

.quantity-conservation strong {
  color: var(--green-dark);
  font-size: 20px;
}

.quantity-conservation small {
  color: #527062;
}

.base-ten-scene .model-actions {
  grid-column: 1 / -1;
}

/* Place value */
.place-value-scene {
  width: min(100%, 620px);
  display: grid;
  gap: 18px;
}

.place-table {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  overflow: hidden;
  background: white;
  border: 2px solid #cdd7d1;
  border-radius: 20px;
  box-shadow: 0 7px 0 rgba(53,75,66,0.08);
}

.place-column {
  min-height: 245px;
  position: relative;
  display: grid;
  grid-template-rows: auto 1fr auto;
}

.place-column + .place-column {
  border-left: 2px solid #cdd7d1;
}

.place-heading {
  padding: 10px;
  display: flex;
  flex-direction: column;
  align-items: center;
  color: var(--teal-dark);
  background: var(--teal-pale);
}

.place-column--ones .place-heading {
  color: var(--blue-dark);
  background: var(--blue-pale);
}

.place-heading span {
  font-size: 17px;
  font-weight: 950;
}

.place-heading small {
  font-size: 9px;
  font-weight: 750;
}

.place-content {
  padding: 18px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 7px;
}

.place-content i {
  color: var(--ink-faint);
  font-size: 34px;
  font-style: normal;
  font-weight: 800;
}

.mini-ten {
  width: 23px;
  height: 100px;
  display: block;
  background: repeating-linear-gradient(180deg, #32a1b0 0 8px, #a5e0e5 8px 9px);
  border: 2px solid var(--teal-dark);
  border-radius: 5px;
}

.mini-one {
  width: 26px;
}

.place-column > strong {
  padding: 8px;
  color: white;
  background: var(--teal);
  font-size: 28px;
  text-align: center;
}

.place-column--ones > strong {
  background: var(--blue);
}

.place-number {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--ink-soft);
  font-size: 14px;
  font-weight: 800;
}

.place-number strong {
  padding: 5px 12px;
  color: white;
  background: var(--accent);
  border-radius: 10px;
  font-size: 25px;
}

/* Equations */
.equation-scene {
  width: min(100%, 700px);
  display: grid;
  gap: 18px;
}

.source-equation,
.final-equation {
  justify-self: center;
  padding: 9px 18px;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border: 1px solid color-mix(in srgb, var(--accent) 24%, white);
  border-radius: 13px;
  font-size: 25px;
  font-weight: 950;
}

.equation-flow {
  display: grid;
  gap: 9px;
}

.equation-card {
  min-height: 56px;
  padding: 9px 14px;
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  align-items: center;
  gap: 12px;
  color: var(--ink);
  background: white;
  border: 1px solid #d7dfd9;
  border-radius: 14px;
  box-shadow: 0 4px 0 rgba(47,65,59,0.06);
  animation: equation-in 850ms var(--ease-out) var(--delay, 0ms) both;
}

.equation-card span {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--accent);
  border-radius: 9px;
  font-size: 10px;
  font-weight: 900;
}

.equation-card strong {
  font-size: clamp(15px, 2vw, 21px);
}

.equation-card--main {
  grid-template-columns: 1fr;
  text-align: center;
}

.final-equation {
  color: white;
  background: var(--green);
  border-color: var(--green-dark);
}

/* Arrays and groups */
.array-scene {
  width: min(100%, 650px);
  display: grid;
  grid-template-columns: 60px minmax(250px, 1fr) 80px;
  align-items: center;
  gap: 16px;
}

.array-board {
  min-height: 230px;
  padding: 20px;
  display: grid;
  grid-template-columns: repeat(var(--columns), minmax(34px, 1fr));
  grid-template-rows: repeat(var(--rows), minmax(34px, 1fr));
  gap: 10px;
  background: #f7f2ff;
  border: 2px solid #c9b9ee;
  border-radius: 22px;
  box-shadow: inset 0 -8px 0 rgba(83,55,151,0.05), 0 7px 0 rgba(83,55,151,0.08);
}

.array-cell {
  min-width: 34px;
  min-height: 34px;
  padding: 0;
  display: grid;
  place-items: center;
  background: rgba(255,255,255,0.7);
  border: 1px dashed #bba9df;
  border-radius: 10px;
}

button.array-cell {
  cursor: pointer;
}

button.array-cell:disabled {
  cursor: default;
  opacity: 1;
}

.array-cell.is-filled {
  border-style: solid;
  background: white;
}

.array-cell span,
.equal-group i,
.scattered-dots span {
  width: 26px;
  aspect-ratio: 1;
  display: block;
  background: #8b6bd3;
  border: 2px solid var(--violet-dark);
  border-radius: 50%;
  box-shadow: inset -3px -3px 0 rgba(61,37,120,0.12), 0 3px 0 rgba(83,55,151,0.13);
}

.array-cell.is-filled span {
  animation: dot-arrive 1000ms var(--ease-out) var(--delay, 0ms) both;
}

.array-dim {
  display: flex;
  flex-direction: column;
  align-items: center;
  color: var(--violet-dark);
}

.array-dim strong {
  font-size: 28px;
}

.array-dim span {
  font-size: 10px;
  font-weight: 850;
}

.array-equation,
.groups-total {
  grid-column: 1 / -1;
  justify-self: center;
  padding: 8px 14px;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--violet-dark);
  background: var(--violet-pale);
  border: 1px solid #d7c9f4;
  border-radius: 13px;
  font-size: 12px;
  font-weight: 800;
}

.array-equation strong,
.groups-total strong {
  font-size: 22px;
}

.array-scene .model-actions {
  grid-column: 1 / -1;
}

.scattered-dots {
  grid-column: 1 / -1;
  grid-row: 1 / -1;
  position: relative;
}

.scattered-dots span {
  position: absolute;
  left: var(--x);
  top: var(--y);
  transform: rotate(calc(var(--x) * 0.1));
}

.placement-count {
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 800;
}

.groups-scene {
  width: min(100%, 760px);
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  justify-content: center;
  gap: 12px;
}

.equal-group {
  min-width: 150px;
  padding: 12px;
  display: grid;
  gap: 8px;
  background: var(--violet-pale);
  border: 1px solid #d5c8ef;
  border-radius: 18px;
}

.equal-group > span,
.equal-group > strong {
  font-size: 10px;
  font-weight: 850;
  text-align: center;
}

.equal-group div {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 5px;
}

.equal-group i {
  width: 23px;
}

.groups-total {
  flex-basis: 100%;
}

/* Comparison, bond, number line */
.comparison-scene {
  width: min(100%, 680px);
  display: grid;
  grid-template-columns: 1fr 70px 1fr;
  align-items: end;
  gap: 18px;
}

.compare-side {
  display: grid;
  gap: 8px;
  text-align: center;
}

.compare-side > span {
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 800;
}

.compare-bar {
  min-height: 150px;
  padding: 12px;
  display: flex;
  flex-wrap: wrap;
  align-content: end;
  justify-content: center;
  gap: 6px;
  background: var(--blue-pale);
  border: 1px solid #c9d8f5;
  border-radius: 18px 18px 6px 6px;
}

.compare-side:last-of-type .compare-bar {
  background: var(--orange-pale);
  border-color: #efd0aa;
}

.compare-bar i {
  width: 26px;
  aspect-ratio: 1;
  background: var(--blue);
  border: 2px solid var(--blue-dark);
  border-radius: 50%;
}

.compare-side:last-of-type .compare-bar i {
  background: var(--orange);
  border-color: var(--orange-dark);
}

.compare-side > strong {
  font-size: 25px;
}

.compare-sign {
  align-self: center;
  width: 58px;
  height: 58px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--accent);
  border-radius: 17px;
  font-size: 30px;
  font-weight: 950;
}

.compare-result {
  grid-column: 1 / -1;
  margin: 0;
  color: var(--green-dark);
  font-size: 13px;
  font-weight: 900;
  text-align: center;
}

.number-bond-scene {
  width: min(100%, 440px);
  display: grid;
  justify-items: center;
}

.bond-whole,
.bond-part {
  min-width: 115px;
  padding: 9px 14px;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--green-pale);
  border: 2px solid #a9d5ba;
  border-radius: 18px;
}

.bond-whole span,
.bond-part span {
  color: var(--ink-soft);
  font-size: 9px;
  font-weight: 800;
}

.bond-whole strong,
.bond-part strong {
  font-size: 25px;
}

.number-bond-scene svg {
  width: 240px;
  height: 90px;
  fill: none;
  stroke: #8ba29a;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.bond-parts {
  width: 100%;
  display: flex;
  justify-content: space-between;
  gap: 35px;
}

.bond-part--0 {
  color: var(--blue-dark);
  background: var(--blue-pale);
  border-color: #b9cdf4;
}

.bond-part--1 {
  color: var(--orange-dark);
  background: var(--orange-pale);
  border-color: #ecc79c;
}

.number-line-scene {
  width: min(100%, 820px);
  overflow-x: auto;
  padding: 44px 22px 20px;
}

.number-line-track {
  min-width: 600px;
  position: relative;
  display: flex;
  justify-content: space-between;
}

.number-line-track::before {
  content: "";
  position: absolute;
  top: 7px;
  right: 0;
  left: 0;
  height: 4px;
  background: #83959a;
  border-radius: 999px;
}

.number-tick {
  position: relative;
  min-width: 18px;
  display: grid;
  justify-items: center;
  gap: 8px;
}

.number-tick i {
  z-index: 1;
  width: 5px;
  height: 17px;
  background: #65797f;
  border-radius: 3px;
}

.number-tick b {
  font-size: 10px;
}

.number-tick.is-start i,
.number-tick.is-end i {
  width: 15px;
  height: 15px;
  background: var(--accent);
  border: 3px solid white;
  border-radius: 50%;
  box-shadow: 0 0 0 2px var(--accent);
}

.jump-list {
  margin-top: 22px;
  display: flex;
  justify-content: center;
  gap: 8px;
}

.jump-list span {
  padding: 5px 10px;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border-radius: 9px;
  font-size: 11px;
  font-weight: 900;
}

.generic-model {
  display: grid;
  justify-items: center;
  color: var(--ink-soft);
}

.generic-model > span {
  color: var(--accent);
  font-size: 45px;
}

.generic-model pre {
  max-width: 100%;
  max-height: 180px;
  overflow: auto;
  font-size: 9px;
  text-align: left;
}

.model-actions {
  margin-top: 8px;
}

.math-action,
.math-reset {
  padding: 10px 15px;
}

.math-action--secondary {
  color: var(--accent-dark);
  background: var(--accent-pale);
  border-color: color-mix(in srgb, var(--accent) 35%, white);
  box-shadow: 0 3px 0 color-mix(in srgb, var(--accent) 22%, white);
}

.math-reset {
  min-width: 48px;
  color: var(--ink-soft);
  background: white;
}

/* Practice and summary */
.practice-shell {
  width: 100%;
}

.practice-topline {
  margin-bottom: 10px;
  display: flex;
  justify-content: space-between;
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 850;
}

.practice-shell .model-frame {
  min-height: 310px;
  padding-top: 38px;
  box-shadow: none;
}

.practice-shell--direct .model-frame {
  padding-top: 20px;
  border-color: color-mix(in srgb, var(--accent) 20%, var(--line));
  background: linear-gradient(180deg, color-mix(in srgb, var(--accent-pale) 28%, white), white 44%);
}

.direct-mode-badge {
  width: fit-content;
  margin: 0 auto 2px;
  padding: 6px 10px;
  display: inline-grid;
  grid-template-columns: 24px auto;
  align-items: center;
  column-gap: 6px;
  color: var(--accent-dark);
  background: var(--accent-pale);
  border: 1px solid color-mix(in srgb, var(--accent) 23%, white);
  border-radius: 999px;
}

.direct-mode-badge > span {
  width: 24px;
  height: 24px;
  grid-row: 1 / 3;
  display: grid;
  place-items: center;
  color: white;
  background: var(--accent);
  border-radius: 50%;
  font-weight: 900;
}

.direct-mode-badge strong { font-size: 10px; }
.direct-mode-badge small { font-size: 8px; }

.direct-check-panel {
  width: min(100%, 720px);
  margin: 12px auto 0;
  padding: 13px;
  background: #fffdf8;
  border: 1px solid var(--line);
  border-radius: 17px;
  box-shadow: 0 8px 20px rgba(45, 62, 61, 0.05);
}

.direct-ready-copy {
  margin: 0 0 10px;
  color: var(--ink-soft);
  font-size: 10px;
  text-align: center;
}

.tiered-hint {
  margin-bottom: 11px;
  padding: 10px 12px;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  color: #744118;
  background: var(--orange-pale);
  border: 1px solid #f2c99d;
  border-radius: 13px;
  animation: reveal-soft 520ms var(--ease-out) both;
}

.tiered-hint span {
  padding: 4px 7px;
  background: white;
  border-radius: 8px;
  font-size: 9px;
  font-weight: 900;
  white-space: nowrap;
}

.tiered-hint p {
  margin: 0;
  font-size: 11px;
  font-weight: 750;
}

.direct-check-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
}

.direct-check-actions .control-button {
  min-height: 46px;
}

.direct-replay-button {
  color: var(--violet-dark);
  background: var(--violet-pale);
  border-color: #cfc0f0;
}

.answer-grid {
  width: min(100%, 690px);
  margin: 16px auto 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
}

.answer-button {
  padding: 10px 12px;
  color: var(--ink);
  background: white;
  border-width: 2px;
}

.answer-button.is-selected {
  border-color: var(--orange);
  background: var(--orange-pale);
}

.answer-button.is-correct {
  color: var(--green-dark);
  background: var(--green-pale);
  border-color: var(--green);
}

.answer-button.is-correct:disabled {
  opacity: 1;
}

.success-banner {
  width: min(100%, 520px);
  margin: 13px auto 0;
  padding: 10px 13px;
  display: grid;
  grid-template-columns: 34px 1fr;
  align-items: center;
  column-gap: 10px;
  color: var(--green-dark);
  background: var(--green-pale);
  border: 1px solid #b8dec7;
  border-radius: 14px;
  animation: rise-in 650ms var(--ease-out) both;
}

.success-banner > span {
  width: 34px;
  height: 34px;
  grid-row: 1 / 3;
  display: grid;
  place-items: center;
  color: white;
  background: var(--green);
  border-radius: 50%;
  font-weight: 900;
}

.success-banner strong {
  font-size: 12px;
}

.success-banner small {
  font-size: 9px;
}

.summary-card {
  width: min(100%, 620px);
  padding: 24px;
  display: grid;
  justify-items: center;
  background: white;
  border: 1px solid #d8e1db;
  border-radius: 26px;
  box-shadow: 0 12px 30px rgba(47,67,60,0.09);
}

.summary-orbit {
  width: 90px;
  height: 90px;
  display: grid;
  place-items: center;
  background: conic-gradient(var(--green) 0 82%, #e6eee8 82%);
  border-radius: 50%;
}

.summary-orbit span {
  width: 68px;
  height: 68px;
  display: grid;
  place-items: center;
  color: white;
  background: var(--green);
  border: 7px solid white;
  border-radius: 50%;
  font-size: 28px;
  font-weight: 950;
}

.summary-card > p {
  margin: 14px 0 0;
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 800;
}

.summary-card > strong {
  color: var(--green-dark);
  font-size: 34px;
}

.summary-card h3 {
  margin: 3px 0 12px;
  font-size: 19px;
}

.summary-card ul {
  width: 100%;
  margin: 0 0 18px;
  padding: 0;
  display: grid;
  gap: 7px;
  list-style: none;
}

.summary-card li {
  padding: 8px 11px;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--ink-soft);
  background: #f6f8f5;
  border-radius: 10px;
  font-size: 10px;
  font-weight: 700;
}

.summary-card li span {
  color: var(--green);
  font-weight: 950;
}

.next-course-card {
  width: 100%;
  margin: 0 0 16px;
  padding: 14px;
  display: grid;
  justify-items: start;
  color: var(--teal-dark);
  background: linear-gradient(135deg, var(--teal-pale), #f5fbf7);
  border: 1px solid #b9dedb;
  border-radius: 16px;
  text-align: left;
}

.next-course-card > span {
  font-size: 9px;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.next-course-card > strong {
  margin-top: 3px;
  color: var(--ink);
  font-size: 13px;
}

.next-course-card > p {
  margin: 4px 0 10px;
  color: var(--ink-soft);
  font-size: 10px;
}

.next-course-card button {
  min-height: 40px;
  padding: 8px 11px;
  color: white;
  background: var(--teal);
  border: 0;
  border-radius: 11px;
  font-size: 10px;
  font-weight: 850;
  cursor: pointer;
}

.site-footer {
  padding: 34px 20px 42px;
  color: var(--ink-faint);
  font-size: 11px;
  font-weight: 700;
  text-align: center;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

@keyframes stage-in {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes sentence-in {
  from { opacity: 0; transform: translateX(8px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes counter-in {
  from { opacity: 0; transform: translateY(18px) scale(0.72); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes cube-in {
  from { opacity: 0; transform: translate(18px, 14px) scale(0.7); }
  to { opacity: 1; transform: translate(0, 0) scale(1); }
}

@keyframes rod-in {
  from { opacity: 0; transform: scaleY(0.28) translateY(28px); }
  to { opacity: 1; transform: scaleY(1) translateY(0); }
}

@keyframes equation-in {
  from { opacity: 0; transform: translateX(-15px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes dot-arrive {
  from { opacity: 0; transform: translate(16px, -18px) scale(0.62); }
  to { opacity: 1; transform: translate(0, 0) scale(1); }
}

@keyframes rise-in {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Phase 6: reusable visual math tools */
.role-card-row,
.paired-equations {
  width: min(100%, 760px);
  margin: 0 auto 16px;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

.role-card,
.paired-equations > div {
  min-width: 112px;
  padding: 11px 14px;
  display: grid;
  gap: 3px;
  color: var(--ink);
  background: white;
  border: 1px solid color-mix(in srgb, var(--accent) 24%, white);
  border-radius: 14px;
  box-shadow: 0 5px 0 color-mix(in srgb, var(--accent) 8%, transparent);
  text-align: center;
}

.role-card span,
.paired-equations span {
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 800;
}

.role-card strong,
.paired-equations strong {
  font-size: 19px;
}

.split-array-scene {
  width: min(100%, 840px);
  margin: auto;
  display: grid;
  grid-template-columns: 70px minmax(0, 1fr);
  gap: 13px;
  align-items: stretch;
}

.split-array-rows {
  display: grid;
  place-content: center;
  color: var(--violet-dark);
  background: var(--violet-pale);
  border-radius: 18px;
  text-align: center;
}

.split-array-rows strong {
  font-size: 34px;
}

.split-array-board {
  min-height: 210px;
  padding: 10px;
  display: flex;
  gap: 8px;
  background: #f8f4ff;
  border: 2px solid #c9b9ee;
  border-radius: 22px;
}

.array-region {
  min-width: 76px;
  padding: 16px 10px;
  flex: var(--part) 1 0;
  display: grid;
  place-content: center;
  gap: 7px;
  color: var(--violet-dark);
  background-color: white;
  background-image: linear-gradient(rgba(139,107,211,.12) 1px, transparent 1px), linear-gradient(90deg, rgba(139,107,211,.12) 1px, transparent 1px);
  background-size: 20px 20px;
  border: 2px solid color-mix(in srgb, var(--violet) 45%, white);
  border-radius: 15px;
  text-align: center;
}

.array-region:nth-child(2n) {
  color: var(--blue-dark);
  background-color: var(--blue-pale);
  border-color: color-mix(in srgb, var(--blue) 45%, white);
}

.array-region > span { font-size: 12px; font-weight: 900; }
.array-region > strong { font-size: 18px; }
.array-region > small { font-size: 26px; font-weight: 950; }

.split-total {
  grid-column: 2;
  display: flex;
  justify-content: center;
  gap: 14px;
  align-items: baseline;
  font-weight: 850;
}

.split-total strong { color: var(--violet-dark); font-size: 24px; }
.split-array-scene .model-actions { grid-column: 1 / -1; }

.equal-group.is-compact > div {
  min-height: 74px;
  display: grid;
  place-content: center;
  gap: 4px;
  color: var(--violet-dark);
  background: repeating-linear-gradient(90deg, rgba(139,107,211,.12) 0 12px, transparent 12px 14px);
  border-radius: 12px;
  font-style: normal;
}

.equal-group.is-compact b,
.equal-group.is-compact em {
  font-style: normal;
  font-size: 12px;
}

.match-meter {
  width: min(100%, 430px);
  margin: 4px auto;
  display: grid;
  gap: 5px;
}

.match-meter::before {
  content: '';
  height: 8px;
  grid-area: 1 / 1;
  background: #e9eeeb;
  border-radius: 999px;
}

.match-meter > span {
  width: calc(var(--matched) * 100%);
  height: 8px;
  z-index: 1;
  grid-area: 1 / 1;
  background: var(--teal);
  border-radius: 999px;
  transition: width 720ms var(--ease-out);
}

.match-meter small { text-align: center; font-weight: 750; color: var(--ink-soft); }

.double-ten-scene,
.subtraction-scene,
.measurement-scene,
.sharing-scene,
.clock-scene,
.symmetry-scene,
.data-chart-scene,
.fraction-bar-scene,
.fraction-shape-scene,
.object-counter-scene,
.part-whole-scene,
.shape-measure-scene,
.shape-challenge-scene {
  width: min(100%, 850px);
  margin: auto;
}

.double-ten-scene {
  display: grid;
  grid-template-columns: minmax(300px, 560px) 140px;
  align-items: center;
  justify-content: center;
  gap: 20px;
}

.double-ten-board {
  padding: 14px;
  display: grid;
  grid-template-columns: repeat(10, minmax(24px, 1fr));
  gap: 6px;
  background: white;
  border: 3px solid var(--blue-dark);
  border-radius: 20px;
  box-shadow: inset 0 -7px 0 rgba(45,104,222,.08), 0 8px 0 rgba(45,104,222,.08);
}

.double-ten-cell {
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  background: #f7faf9;
  border: 1px solid #cfd8d2;
  border-radius: 8px;
}

.double-ten-cell i,
.take-token i,
.object-row i,
.share-plate i {
  width: 72%;
  aspect-ratio: 1;
  display: block;
  background: var(--blue);
  border: 2px solid var(--blue-dark);
  border-radius: 50%;
  box-shadow: inset -3px -3px 0 rgba(17,63,145,.14), 0 3px 0 rgba(45,104,222,.13);
}

.double-ten-cell.is-marked i {
  background: var(--orange);
  border-color: #a94e22;
}

.double-ten-summary,
.subtraction-status,
.measure-reading,
.fair-result,
.property-answer {
  padding: 15px;
  display: grid;
  gap: 3px;
  color: var(--ink-soft);
  background: white;
  border: 1px solid var(--line);
  border-radius: 17px;
  text-align: center;
}

.double-ten-summary strong,
.subtraction-status strong,
.measure-reading strong,
.fair-result strong,
.property-answer strong {
  color: var(--accent-dark);
  font-size: 34px;
}

.subtraction-scene {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 160px;
  gap: 16px;
  align-items: center;
}

.take-board {
  min-height: 180px;
  padding: 18px;
  display: grid;
  grid-template-columns: repeat(10, minmax(28px, 1fr));
  gap: 9px;
  align-content: center;
  background: var(--blue-pale);
  border: 2px solid color-mix(in srgb, var(--blue) 38%, white);
  border-radius: 22px;
}

.take-token {
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  transition: opacity 850ms ease, transform 850ms var(--ease-out);
}

.take-token.is-removed {
  opacity: .18;
  transform: translateY(-12px) scale(.72);
}

.bridge-parts {
  grid-column: 1 / -1;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 900;
}

.bridge-parts span {
  min-width: 46px;
  padding: 8px;
  color: var(--blue-dark);
  background: white;
  border: 2px solid color-mix(in srgb, var(--blue) 30%, white);
  border-radius: 13px;
  text-align: center;
}

.subtraction-scene .model-actions { grid-column: 1 / -1; }

.object-counter-scene {
  display: grid;
  gap: 12px;
}

.object-row {
  padding: 14px 18px;
  display: grid;
  grid-template-columns: 70px minmax(0, 1fr) 48px;
  align-items: center;
  gap: 12px;
  background: white;
  border: 1px solid var(--line);
  border-radius: 18px;
}

.object-row > div {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.object-row i { width: 30px; }
.object-row--orange i { background: var(--orange); border-color: #a94e22; }
.object-row strong { font-size: 24px; }
.object-counter-scene p,
.part-whole-scene p,
.symmetry-scene p,
.data-chart-scene p,
.fraction-bar-scene p,
.fraction-shape-scene p,
.shape-measure-scene > p { margin: 4px 0 0; color: var(--ink-soft); text-align: center; font-weight: 750; }

.part-whole-scene { display: grid; gap: 10px; }
.whole-strip { padding: 13px 18px; display: flex; justify-content: space-between; color: white; background: var(--blue); border-radius: 17px; }
.part-strip { display: flex; gap: 8px; }
.part-piece { padding: 16px; flex: var(--part) 1 0; display: flex; justify-content: space-between; color: var(--teal-dark); background: var(--teal-pale); border: 2px solid color-mix(in srgb, var(--teal) 30%, white); border-radius: 16px; }
.part-piece--1 { color: #a94e22; background: var(--orange-pale); border-color: color-mix(in srgb, var(--orange) 35%, white); }

.measurement-scene { display: grid; gap: 16px; }
.measure-object { display: grid; grid-template-columns: auto minmax(200px, 1fr) auto; gap: 9px; align-items: center; color: var(--ink-soft); font-size: 11px; font-weight: 850; }
.measure-object > div { height: 20px; background: linear-gradient(90deg, var(--orange), var(--yellow)); border: 3px solid #a94e22; border-radius: 999px 20px 20px 999px; box-shadow: 0 5px 0 rgba(169,78,34,.1); }
.unit-track { padding: 12px; display: grid; grid-template-columns: repeat(auto-fit, minmax(42px, 1fr)); gap: 3px; background: white; border: 2px solid color-mix(in srgb, var(--teal) 35%, white); border-radius: 17px; }
.measure-unit { min-height: 58px; display: grid; place-items: end center; color: transparent; background: #edf1ef; border: 1px dashed #bbc7c1; transition: color 650ms ease, background 650ms ease, transform 650ms var(--ease-out); }
.measure-unit.is-placed { color: var(--teal-dark); background: var(--teal-pale); border-style: solid; transform: translateY(0); }
.measure-unit i { font-style: normal; font-size: 11px; font-weight: 900; }
.measure-reading { width: min(100%, 260px); margin: auto; }

.shape-measure-scene { display: grid; grid-template-columns: 230px minmax(250px, 1fr); gap: 22px; align-items: center; }
.property-choice { display: grid; gap: 10px; }
.property-card { min-height: 92px; padding: 12px; display: grid; gap: 3px; color: var(--ink); background: white; border: 2px solid var(--line); border-radius: 17px; cursor: pointer; text-align: left; }
.property-card:disabled { cursor: default; opacity: 1; }
.property-card.is-active { color: var(--teal-dark); background: var(--teal-pale); border-color: var(--teal); box-shadow: 0 0 0 3px rgba(31,157,145,.1); }
.property-card small { color: var(--ink-soft); }
.measure-rectangle,
.mini-grid-shape { padding: 10px; display: grid; grid-template-columns: repeat(var(--columns), 1fr); grid-template-rows: repeat(var(--rows), 1fr); gap: 3px; background: white; border: 5px solid var(--ink); border-radius: 10px; }
.measure-rectangle i,
.mini-grid-shape i { min-height: 34px; background: #fff; border: 1px dashed #b9c5bf; }
.measure-rectangle.show-area i { background: var(--yellow-pale); border-style: solid; }
.measure-rectangle.show-perimeter { border-color: var(--orange); box-shadow: 0 0 0 5px rgba(237,126,75,.14); }
.shape-measure-scene > p { grid-column: 1 / -1; }

.sharing-scene { display: grid; grid-template-columns: 110px minmax(0, 1fr); gap: 16px; align-items: center; }
.share-tray { min-height: 110px; display: grid; place-content: center; color: var(--ink-soft); background: var(--orange-pale); border: 2px dashed var(--orange); border-radius: 50%; text-align: center; }
.share-tray strong { color: #a94e22; font-size: 30px; }
.share-plates { display: grid; grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: 10px; }
.share-plate { min-height: 130px; padding: 11px; display: grid; gap: 8px; background: white; border: 3px solid #cfd8d2; border-radius: 50% 50% 20px 20px; text-align: center; }
.share-plate.is-fair { border-color: var(--teal); background: var(--teal-pale); }
.share-plate > div { display: flex; flex-wrap: wrap; justify-content: center; gap: 4px; }
.share-plate i { width: 19px; background: var(--violet); border-color: var(--violet-dark); }
.fair-result { grid-column: 1 / -1; width: min(100%, 300px); margin: auto; }
.sharing-scene .model-actions { grid-column: 1 / -1; }

.clock-scene { display: grid; grid-template-columns: 250px minmax(220px, 1fr); gap: 25px; align-items: center; justify-content: center; }
.clock-face { width: 240px; aspect-ratio: 1; position: relative; justify-self: center; background: #fffdf6; border: 10px solid var(--blue); border-radius: 50%; box-shadow: inset 0 0 0 4px var(--blue-pale), 0 10px 0 rgba(45,104,222,.1); }
.clock-face > span { width: 26px; height: 26px; position: absolute; left: calc(50% - 13px); top: calc(50% - 13px); display: grid; place-items: center; color: var(--ink); font-size: 12px; font-weight: 900; transform: rotate(var(--angle)) translateY(-92px) rotate(calc(var(--angle) * -1)); }
.clock-face > b { width: 16px; aspect-ratio: 1; position: absolute; z-index: 4; left: calc(50% - 8px); top: calc(50% - 8px); background: var(--orange); border: 3px solid white; border-radius: 50%; box-shadow: 0 2px 5px rgba(0,0,0,.2); }
.clock-hand { width: 6px; position: absolute; z-index: 2; left: calc(50% - 3px); bottom: 50%; display: block; background: var(--ink); border-radius: 999px 999px 4px 4px; transform: rotate(var(--angle)); transform-origin: 50% 100%; transition: transform 1100ms var(--ease-out); }
.clock-hand--hour { height: 57px; }
.clock-hand--minute { width: 4px; height: 79px; left: calc(50% - 2px); background: var(--blue); }
.time-journey { padding: 22px; display: grid; grid-template-columns: 1fr auto 1fr; gap: 10px; align-items: center; background: white; border: 1px solid var(--line); border-radius: 20px; text-align: center; }
.time-journey strong { color: var(--blue-dark); font-size: 32px; }
.time-journey small { grid-column: 1 / -1; color: var(--ink-soft); font-weight: 800; }
.clock-scene .model-actions { grid-column: 1 / -1; }

.symmetry-scene { display: grid; gap: 14px; }
.symmetry-board { min-height: 250px; padding: 24px; position: relative; display: grid; grid-template-columns: 1fr 16px 1fr; gap: 6px; overflow: hidden; background-color: #f9f6ff; background-image: linear-gradient(rgba(139,107,211,.1) 1px, transparent 1px), linear-gradient(90deg, rgba(139,107,211,.1) 1px, transparent 1px); background-size: 25px 25px; border: 2px solid #c9b9ee; border-radius: 22px; perspective: 700px; }
.symmetry-axis { z-index: 3; display: grid; place-items: center; border-left: 3px dashed var(--violet); }
.symmetry-axis span { padding: 5px; color: var(--violet-dark); background: white; border-radius: 8px; font-size: 10px; font-weight: 900; writing-mode: vertical-rl; }
.shape-half { position: relative; display: grid; place-content: center; gap: 8px; transition: transform 1200ms var(--ease-out), opacity 700ms ease; transform-origin: right center; }
.shape-half--right { transform-origin: left center; }
.shape-half i { width: clamp(46px, 8vw, 78px); height: 42px; display: block; background: var(--violet); border: 3px solid var(--violet-dark); border-radius: 70% 35% 65% 35%; box-shadow: inset -5px -5px 0 rgba(61,37,120,.12); }
.shape-half--right i { transform: scaleX(-1); }
.symmetry-board.is-folded .shape-half--right { opacity: .35; transform: rotateY(-180deg); }
.symmetry-board.has-mismatch .shape-half--right i:last-child { transform: scaleX(-.72); background: var(--orange); }

.symmetry-board[data-axis="none"] .symmetry-axis {
  opacity: 0.32;
}

.symmetry-board[data-axis="horizontal"] {
  transform: rotate(90deg) scale(0.8);
}

.symmetry-board[data-axis="diagonal"] {
  transform: rotate(42deg) scale(0.8);
}

.symmetry-board.has-selected-axis {
  transition: transform 900ms var(--ease-out), box-shadow 500ms ease;
  box-shadow: 0 0 0 4px rgba(120, 86, 200, 0.1);
}

.axis-choice {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.axis-choice button {
  min-height: 48px;
  color: var(--violet-dark);
  background: white;
  border: 2px solid #d8cdf1;
  border-radius: 13px;
  font-size: 12px;
  font-weight: 850;
  cursor: pointer;
}

.axis-choice button.is-selected {
  color: white;
  background: var(--violet);
  border-color: var(--violet-dark);
  box-shadow: 0 5px 0 rgba(83, 55, 151, 0.18);
}

.shape-challenge-scene { display: flex; align-items: center; justify-content: center; gap: 24px; }
.mini-grid-shape { width: min(100%, 300px); min-height: 190px; }

.shape-challenge-scene--direct {
  display: grid;
  grid-template-columns: minmax(220px, 0.8fr) minmax(260px, 1fr);
}

.direct-property-choice {
  grid-template-columns: repeat(2, minmax(120px, 1fr));
}

.shape-challenge-scene--direct .property-answer {
  grid-column: 1 / -1;
  justify-self: center;
}

.data-chart-scene { display: grid; gap: 12px; }
.chart-plot { min-height: 270px; padding: 28px 24px 34px 45px; position: relative; display: flex; align-items: flex-end; justify-content: space-around; gap: 20px; background-color: white; background-image: linear-gradient(rgba(31,65,71,.08) 1px, transparent 1px); background-size: 100% 28px; border: 1px solid var(--line); border-radius: 22px; }
.chart-baseline { height: 3px; position: absolute; right: 20px; bottom: 34px; left: 35px; background: var(--ink); }
.chart-baseline span { position: absolute; left: -20px; top: -8px; font-size: 11px; font-weight: 900; }
.data-bar-wrap { height: 210px; flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: flex-end; gap: 6px; }
.data-bar { width: min(78px, 80%); min-height: 2px; height: calc(var(--value) * 28px); padding: 4px; position: relative; display: flex; flex-direction: column-reverse; background: var(--teal-pale); border: 2px solid var(--teal); border-bottom: 0; border-radius: 10px 10px 0 0; transition: height 900ms var(--ease-out); }
.data-bar span { position: absolute; top: -25px; left: 0; right: 0; color: var(--teal-dark); font-weight: 950; text-align: center; }
.data-bar i { min-height: 22px; border-top: 1px solid rgba(31,157,145,.25); }
.data-bar-wrap:nth-of-type(3n) .data-bar { background: var(--blue-pale); border-color: var(--blue); }
.data-bar-wrap:nth-of-type(4n) .data-bar { background: var(--violet-pale); border-color: var(--violet); }
.data-bar-wrap > strong { min-height: 20px; font-size: 12px; }
.mean-line { height: 0; position: absolute; right: 18px; bottom: calc(34px + var(--mean) * 28px); left: 35px; border-top: 3px dashed var(--orange); }
.mean-line span { position: absolute; right: 0; bottom: 5px; padding: 3px 7px; color: #a94e22; background: var(--orange-pale); border-radius: 7px; font-size: 10px; font-weight: 900; }

.fraction-bars { display: grid; gap: 15px; }
.fraction-bar-row { display: grid; grid-template-columns: 100px minmax(260px, 1fr) 55px; gap: 12px; align-items: center; }
.fraction-bar-row > span { color: var(--ink-soft); font-size: 11px; font-weight: 800; }
.fraction-whole { height: 78px; display: grid; grid-template-columns: repeat(var(--parts), 1fr); overflow: hidden; background: white; border: 3px solid var(--blue-dark); border-radius: 13px; }
.fraction-whole i { border-right: 1px solid var(--blue-dark); }
.fraction-whole i:last-child { border-right: 0; }
.fraction-whole i.is-selected { background: var(--yellow); box-shadow: inset -4px -4px 0 rgba(169,78,34,.1); }
.fraction-bar-row strong { color: var(--blue-dark); font-size: 21px; }
.fraction-choice {
  width: 100%;
  padding: 10px;
  color: var(--ink);
  background: white;
  border: 2px solid var(--line);
  border-radius: 16px;
  cursor: pointer;
  text-align: left;
  transition: transform 300ms var(--ease-out), border-color 300ms ease, box-shadow 300ms ease;
}

.fraction-choice:hover {
  border-color: #9fbae9;
  transform: translateY(-2px);
}

.fraction-choice.is-selected {
  border-color: var(--blue);
  box-shadow: 0 0 0 4px rgba(47, 111, 237, 0.1);
}
.fraction-result { width: fit-content; margin: 16px auto 0; padding: 10px 18px; color: var(--blue-dark); background: var(--blue-pale); border-radius: 14px; font-size: 23px; font-weight: 950; }
.fraction-compare-scene { display: grid; grid-template-columns: 1fr auto 1fr; gap: 18px; align-items: center; }
.unit-fraction-piece { display: grid; place-items: center; gap: 7px; text-align: center; }
.unit-fraction-piece > div { width: var(--piece-width); max-width: 100%; height: 76px; background: var(--yellow); border: 3px solid #a94e22; border-radius: 13px; box-shadow: inset -5px -5px 0 rgba(169,78,34,.11); }
.unit-fraction-piece strong { font-size: 23px; }
.unit-fraction-piece small { color: var(--ink-soft); }
.fraction-compare-scene > p { grid-column: 1 / -1; margin: 0; text-align: center; font-weight: 800; }
.fraction-shapes { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 16px; }
.partition-shape { padding: 15px; display: grid; gap: 8px; background: white; border: 2px solid var(--line); border-radius: 18px; text-align: center; }
.partition-shape.is-active { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(45,104,222,.1); }
.partition-shape > div { height: 110px; display: grid; grid-template-columns: repeat(var(--parts), 1fr); overflow: hidden; border: 3px solid var(--blue-dark); border-radius: 14px; }
.partition-shape i { border-right: 1px solid var(--blue-dark); }
.partition-shape i.is-selected { background: var(--yellow); }

.label-line-track {
  min-height: 120px;
  padding: 0 22px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.label-line-track::before {
  content: '';
  height: 5px;
  position: absolute;
  right: 22px;
  left: 22px;
  background: var(--blue);
  border-radius: 999px;
}

.label-tick {
  min-width: 54px;
  z-index: 1;
  display: grid;
  place-items: center;
  gap: 8px;
}

.label-tick i { width: 4px; height: 24px; background: var(--blue-dark); border-radius: 4px; }
.label-tick b { padding: 4px 7px; background: white; border: 1px solid var(--line); border-radius: 8px; font-size: 12px; }
.label-tick.is-start b,
.label-tick.is-end b { color: white; background: var(--blue); }

/* Expansion batch 1: visual math models */
.five-frame-scene {
  width: min(100%, 720px);
  display: grid;
  grid-template-columns: minmax(320px, 1fr) 150px;
  gap: 24px;
  align-items: center;
}

.five-board {
  padding: 16px;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  background: white;
  border: 4px solid var(--teal-dark);
  border-radius: 22px;
  box-shadow: inset 0 -8px 0 rgba(31,157,145,.08), 0 9px 0 rgba(17,98,101,.1);
}

.five-cell {
  min-height: 94px;
  display: grid;
  place-items: center;
  color: var(--ink-faint);
  background: #f5f8f6;
  border: 1px solid #cad6d0;
  border-radius: 14px;
}

.five-cell i {
  width: 64%;
  aspect-ratio: 1;
  background: var(--blue);
  border: 3px solid var(--blue-dark);
  border-radius: 50%;
  box-shadow: inset -5px -5px 0 rgba(20,67,159,.15), 0 5px 0 rgba(45,104,222,.12);
  animation: counter-drop 900ms var(--ease-out) both;
}

.five-cell.is-second-group i { background: var(--orange); border-color: #9f421b; }
.five-cell small { font-size: 9px; font-weight: 800; }
.five-reading { padding: 18px; display: grid; gap: 3px; background: var(--teal-pale); border: 1px solid #b9dddd; border-radius: 19px; text-align: center; }
.five-reading strong { color: var(--teal-dark); font-size: 38px; }
.five-reading small { color: var(--ink-soft); font-weight: 750; }

.addition-machine-scene { width: min(100%, 820px); display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(190px, .7fr); gap: 22px; align-items: stretch; }
.join-parts { display: grid; grid-template-columns: 1fr 70px 1fr; gap: 8px; align-items: center; }
.join-part,
.join-whole { min-height: 190px; padding: 16px; display: grid; align-content: center; gap: 10px; background: white; border: 2px solid var(--line); border-radius: 22px; text-align: center; }
.join-part > div,
.join-whole > div { min-height: 80px; display: flex; flex-wrap: wrap; justify-content: center; align-content: center; gap: 7px; }
.join-part strong,
.join-whole strong { font-size: 30px; }
.join-token { width: 31px; aspect-ratio: 1; display: block; background: var(--blue); border: 2px solid var(--blue-dark); border-radius: 50%; box-shadow: inset -3px -3px 0 rgba(25,66,154,.14); animation: join-token-in 1200ms var(--ease-out) both; }
.join-token--orange { background: var(--orange); border-color: #9f421b; }
.join-token--whole { background: var(--teal); border-color: var(--teal-dark); }
.join-part--blue { color: var(--blue-dark); background: var(--blue-pale); border-color: #b9caed; }
.join-part--orange { color: #9f421b; background: var(--orange-pale); border-color: #eac1ab; }
.join-flow { display: grid; place-items: center; color: var(--ink-soft); font-size: 10px; font-weight: 850; }
.join-flow b { color: var(--orange); font-size: 36px; }
.join-whole { color: var(--teal-dark); background: var(--teal-pale); border-color: #a9d6d2; }
.join-equation { grid-column: 1 / -1; justify-self: center; padding: 10px 18px; color: var(--teal-dark); background: white; border: 2px solid #b9dddd; border-radius: 14px; font-size: 23px; font-weight: 950; animation: sentence-in 900ms var(--ease-out) both; }

.thousand-blocks-scene { width: min(100%, 860px); display: grid; grid-template-columns: minmax(280px, 1.2fr) 100px minmax(220px, .8fr); gap: 18px; align-items: center; }
.hundred-stack,
.thousand-cube-wrap { min-height: 250px; padding: 17px; display: grid; align-content: center; justify-items: center; gap: 10px; background: #fff; border: 2px solid #badbd7; border-radius: 23px; }
.hundred-grid { min-height: 155px; display: grid; grid-template-columns: repeat(5, 54px); gap: 7px; place-content: center; }
.hundred-grid em { grid-column: 1 / -1; align-self: center; color: var(--ink-soft); font-style: normal; font-weight: 800; }
.hundred-flat { width: 54px; height: 65px; display: grid; place-items: center; background: repeating-linear-gradient(0deg, #78c9c2 0 5px, #bce8e4 5px 6px); border: 2px solid var(--teal-dark); border-radius: 7px; box-shadow: 4px 5px 0 rgba(17,98,101,.12); animation: tile-gather 1400ms var(--ease-out) var(--delay,0ms) both; }
.hundred-flat.is-selected { background: var(--yellow); border-color: #9f6910; transform: translateY(-4px); }
.hundred-flat small { padding: 2px 4px; color: var(--teal-dark); background: rgba(255,255,255,.76); border-radius: 5px; font-style: normal; font-weight: 950; }
.unit-caption { padding: 4px 9px; color: white; background: var(--teal); border-radius: 8px; font-size: 10px; font-weight: 900; }
.thousand-exchange { display: grid; place-items: center; gap: 4px; color: var(--ink-soft); text-align: center; }
.thousand-exchange b { color: var(--teal); font-size: 42px; }
.thousand-exchange span,
.thousand-exchange small { font-size: 10px; font-weight: 850; }
.thousand-placeholder { min-height: 150px; display: grid; place-items: center; color: var(--ink-faint); border: 2px dashed #cbd6d0; border-radius: 18px; text-align: center; }
.thousand-cube { width: 150px; aspect-ratio: 1; position: relative; display: grid; place-items: center; background: linear-gradient(135deg, #45b6ad, #177e82); border: 4px solid var(--teal-dark); border-radius: 20px; box-shadow: inset -18px -18px 0 rgba(4,73,79,.14), 12px 14px 0 rgba(17,98,101,.11); animation: thousand-arrive 1800ms var(--ease-out) both; }
.thousand-cube::before { content: ''; position: absolute; inset: 11px; background-image: linear-gradient(rgba(255,255,255,.22) 1px, transparent 1px),linear-gradient(90deg,rgba(255,255,255,.22) 1px,transparent 1px); background-size: 13px 13px; border-radius: 10px; }
.thousand-cube b { z-index: 1; padding: 5px 9px; color: var(--teal-dark); background: white; border-radius: 9px; font-size: 21px; }
.thousand-equivalence { grid-column: 1 / -1; justify-self: center; padding: 10px 16px; display: flex; align-items: center; gap: 10px; background: var(--green-pale); border: 1px solid #c5e3d1; border-radius: 14px; }
.thousand-equivalence strong { color: var(--green-dark); font-size: 20px; }
.thousand-equivalence small { color: var(--ink-soft); }
.thousand-blocks-scene .model-actions { grid-column: 1 / -1; }

.place-value-scene--extended { width: min(100%, 800px); }
.place-value-scene--extended .place-table { grid-template-columns: repeat(var(--place-columns), minmax(100px, 1fr)); }
.place-value-scene--extended .place-column { min-height: 210px; }
.place-value-scene--extended .place-heading { color: var(--teal-dark); background: var(--teal-pale); }
.place-value-scene--extended .place-column--hundreds .place-heading { color: var(--violet-dark); background: var(--violet-pale); }
.place-value-scene--extended .place-column--tens .place-heading { color: #9f421b; background: var(--orange-pale); }
.place-value-scene--extended .place-column--ones .place-heading { color: var(--blue-dark); background: var(--blue-pale); }
.place-value-scene--extended .place-column--tenths .place-heading { color: #8a5d00; background: var(--yellow-pale); }
.place-value-scene--extended .place-column--tenths { border-left: 5px double var(--ink); }
.place-value-scene--extended .place-content em { color: var(--ink-faint); font-size: 28px; font-style: normal; font-weight: 850; }
.place-unit { width: 28px; aspect-ratio: 1; display: block; background: var(--teal); border: 2px solid var(--teal-dark); border-radius: 6px; animation: cube-in 900ms var(--ease-out) both; }
.place-unit--thousands { width: 46px; background-image: linear-gradient(rgba(255,255,255,.28) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.28) 1px,transparent 1px); background-size: 8px 8px; }
.place-unit--hundreds { background: var(--violet); border-color: var(--violet-dark); }
.place-unit--tens { width: 12px; height: 64px; background: var(--orange); border-color: #9f421b; }
.place-unit--ones { background: var(--blue); border-color: var(--blue-dark); }
.place-unit--tenths { width: 22px; background: var(--yellow); border-color: #9f6910; border-radius: 50%; }

.count-object { min-width: 44px; min-height: 44px; position: relative; display: grid; place-items: center; padding: 3px; background: transparent; border: 0; cursor: pointer; }
.count-object i { width: 30px; }
.count-object b { min-width: 19px; height: 19px; position: absolute; right: 0; top: 0; display: grid; place-items: center; color: white; background: var(--teal-dark); border: 2px solid white; border-radius: 50%; font-size: 9px; }
.count-object.is-counted { animation: counted-pop 900ms var(--ease-out) both; }
.counting-result { padding: 11px 15px; display: flex; align-items: center; justify-content: center; gap: 10px; color: var(--ink-soft); background: var(--teal-pale); border: 1px solid #b9dddd; border-radius: 15px; }
.counting-result strong { color: var(--teal-dark); font-size: 24px; }
.counting-result small { font-weight: 750; }
.empty-collection { min-height: 52px; display: grid; place-items: center; color: var(--ink-soft); font-style: normal; font-weight: 850; }
.object-counter-scene .model-actions,
.part-whole-scene .model-actions { justify-self: center; }
.part-whole-scene.is-joined .whole-strip { background: var(--teal); animation: whole-confirm 1000ms var(--ease-out) both; }

.metric-ruler-scene { width: min(100%, 860px); display: grid; gap: 18px; }
.segment-canvas { min-height: 62px; display: grid; grid-template-columns: 34px minmax(260px, 1fr) 34px; align-items: center; color: var(--ink-soft); font-size: 10px; font-weight: 900; }
.metric-segment { height: 9px; display: block; background: linear-gradient(90deg,var(--orange),var(--yellow)); border: 2px solid #9f421b; border-radius: 999px; }
.endpoint { width: 31px; aspect-ratio: 1; display: grid; place-items: center; color: white; background: var(--orange); border-radius: 50%; }
.ruler-wrap { position: relative; padding: 18px 8px 8px; overflow: hidden; background: #fffdf0; border: 2px solid #d7ba63; border-radius: 19px; }
.metric-ruler { min-width: 620px; display: grid; grid-template-columns: repeat(11, 1fr); transform: translateX(calc(var(--ruler-offset) * 5.6%)); transition: transform 1700ms var(--ease-out); }
.ruler-mark { min-height: 94px; position: relative; display: flex; justify-content: center; border-left: 2px solid #775b18; }
.ruler-mark i { width: 1px; height: 42px; background: #775b18; }
.ruler-mark:nth-child(even) i { height: 28px; }
.ruler-mark b { position: absolute; bottom: 8px; font-size: 12px; }
.ruler-mark.is-zero { color: #9f421b; border-left-width: 4px; }
.ruler-zero-guide { position: absolute; z-index: 2; left: 8px; top: 0; display: flex; align-items: center; gap: 4px; color: #9f421b; font-size: 9px; font-weight: 900; }
.ruler-zero-guide i { width: 2px; height: 115px; background: rgba(237,126,75,.34); }
.metric-reading { padding: 12px 17px; justify-self: center; display: grid; grid-template-columns: auto auto; align-items: center; gap: 4px 13px; background: var(--yellow-pale); border: 1px solid #e4cf85; border-radius: 16px; }
.metric-reading strong { color: #8a5d00; font-size: 27px; }
.metric-reading small { grid-column: 1 / -1; color: var(--ink-soft); }

.tenths-lab-scene { width: min(100%, 820px); display: grid; grid-template-columns: 130px minmax(360px,1fr); gap: 18px; align-items: center; }
.whole-one-label,
.tenths-equivalence { padding: 15px; display: grid; gap: 3px; background: white; border: 1px solid var(--line); border-radius: 18px; text-align: center; }
.whole-one-label strong,
.tenths-equivalence strong { color: var(--blue-dark); font-size: 34px; }
.tenths-board { min-height: 120px; display: grid; grid-template-columns: repeat(10,1fr); overflow: hidden; background: white; border: 4px solid var(--blue-dark); border-radius: 18px; box-shadow: 0 9px 0 rgba(45,104,222,.1); }
.tenth-cell { min-width: 0; min-height: 112px; position: relative; display: grid; place-items: center; padding: 0; background: white; border: 0; border-right: 1px solid var(--blue-dark); cursor: pointer; transition: background 1100ms ease, transform 700ms var(--ease-out); }
.tenth-cell:last-child { border-right: 0; }
.tenth-cell.is-selected { background: var(--yellow); box-shadow: inset -3px -5px 0 rgba(159,105,16,.12); }
.tenth-cell i { width: 12px; height: 62px; display: block; background: color-mix(in srgb,var(--yellow) 45%,white); border-radius: 999px; opacity: 0; transform: scaleY(.3); transition: opacity 800ms ease,transform 900ms var(--ease-out); }
.tenth-cell.is-selected i { opacity: 1; transform: scaleY(1); }
.tenth-cell small { position: absolute; bottom: 5px; color: var(--ink-soft); font-size: 8px; font-weight: 800; }
.tenths-equivalence { grid-column: 1 / -1; justify-self: center; min-width: 260px; }
.tenths-lab-scene .model-actions { grid-column: 1 / -1; }

.decimal-compare-scene { width: min(100%,760px); display: grid; grid-template-columns: 1fr 70px 1fr; gap: 16px; align-items: center; }
.decimal-compare-side { display: grid; gap: 8px; text-align: center; }
.decimal-compare-side > span { font-size: 27px; font-weight: 950; }
.decimal-tenths { height: 76px; display: grid; grid-template-columns: repeat(10,1fr); overflow: hidden; border: 3px solid var(--blue-dark); border-radius: 13px; }
.decimal-tenths i { background: white; border-right: 1px solid var(--blue-dark); }
.decimal-tenths i.is-filled { background: var(--blue-pale); }
.decimal-tenths--orange { border-color: #9f421b; }
.decimal-tenths--orange i { border-color: #9f421b; }
.decimal-tenths--orange i.is-filled { background: var(--orange-pale); }
.decimal-compare-scene > p { grid-column: 1 / -1; margin: 0; color: var(--ink-soft); text-align: center; font-weight: 800; }
.decimal-number-line { width: min(100%,840px); display: grid; gap: 16px; }
.decimal-line-track { min-width: 620px; padding: 30px 12px 8px; display: grid; grid-template-columns: repeat(11,1fr); overflow-x: auto; background: white; border: 1px solid var(--line); border-radius: 18px; }
.decimal-tick { min-height: 74px; position: relative; display: grid; justify-items: center; align-content: start; color: var(--ink-soft); }
.decimal-tick::before { content:''; width:100%; height:5px; position:absolute; top:7px; left:50%; background:var(--blue); }
.decimal-tick:last-child::before { display:none; }
.decimal-tick i { width:4px; height:22px; z-index:1; background:var(--blue-dark); border-radius:999px; }
.decimal-tick b { margin-top:8px; font-size:10px; }
.decimal-tick.is-target i { height:34px; background:var(--orange); box-shadow:0 0 0 6px rgba(237,126,75,.14); }
.decimal-number-line p,
.timeline-total { margin: 0; color: var(--ink-soft); text-align: center; font-weight:800; }
.time-segment-line .label-tick small { padding:3px 6px; color:white; background:var(--violet); border-radius:7px; font-size:8px; }
.timeline-total { color:var(--blue-dark); font-size:16px; }
.hundred-hop-line .label-line-track { overflow-x:auto; }
.hundred-hop-line .label-tick { min-width:68px; }

.clock-day { padding: 4px 8px; position: absolute; left: 50%; bottom: 33px; transform: translateX(-50%); color: var(--violet-dark); background: var(--violet-pale); border-radius: 8px; font-size: 9px; font-style: normal; font-weight: 900; }
.clock-pair-scene { width:min(100%,760px); display:grid; grid-template-columns:190px 1fr; gap:18px; align-items:center; }
.clock-pair-orbit { min-height:190px; display:grid; place-content:center; gap:7px; color:white; background:linear-gradient(145deg,var(--violet),var(--blue)); border-radius:50%; box-shadow:0 12px 0 rgba(83,55,151,.12); text-align:center; }
.clock-pair-orbit strong { font-size:20px; }
.clock-pair-list { display:grid; gap:10px; }
.clock-pair-list > div { min-height:70px; padding:12px 16px; display:grid; grid-template-columns:1fr auto 1fr; align-items:center; gap:10px; background:white; border:1px solid var(--line); border-radius:16px; text-align:center; }
.clock-pair-list strong { color:var(--violet-dark); font-size:21px; }
.clock-pair-scene p { grid-column:1/-1; margin:0; color:var(--ink-soft); text-align:center; font-weight:800; }
.clock-conversion-card { width:min(100%,520px); padding:28px; display:grid; grid-template-columns:1fr auto; gap:9px 18px; align-items:center; color:var(--ink-soft); background:linear-gradient(145deg,var(--violet-pale),white); border:2px solid #cabbe9; border-radius:24px; }
.clock-conversion-card strong { color:var(--violet-dark); font-size:33px; }
.clock-conversion-card b { grid-row:1/3; grid-column:2; color:var(--orange); font-size:34px; }
.clock-conversion-card small { grid-column:1/-1; font-weight:800; }

@keyframes join-token-in { from { opacity:0; transform:translateY(-12px) scale(.7); } to { opacity:1; transform:none; } }
@keyframes tile-gather { from { opacity:.25; transform:translateY(18px) rotate(3deg); } to { opacity:1; transform:none; } }
@keyframes thousand-arrive { from { opacity:0; transform:scale(.72) rotate(-4deg); } to { opacity:1; transform:none; } }
@keyframes counted-pop { 0% { transform:scale(.75); } 65% { transform:scale(1.1); } 100% { transform:none; } }
@keyframes whole-confirm { from { transform:scale(.96); } to { transform:none; } }

@media (max-width: 1120px) {
  .runtime-layout {
    grid-template-columns: 250px minmax(0, 1fr);
  }

  .course-panel {
    padding: 17px;
  }

  .course-button {
    grid-template-columns: 42px minmax(0, 1fr) 20px;
  }

  .course-icon {
    width: 42px;
    height: 42px;
  }

  .scene-copy {
    grid-template-columns: 120px minmax(0, 0.65fr) minmax(270px, 1.35fr);
  }

  .ten-frame-scene {
    grid-template-columns: 74px minmax(250px, 1fr) 155px;
    gap: 13px;
  }
}

@media (max-width: 900px) {
  .intro {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .intro-copy {
    max-width: 650px;
  }

  .runtime-layout {
    grid-template-columns: 1fr;
  }

  .course-panel {
    position: static;
  }

  .course-list {
    max-height: none;
    padding-right: 0;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    overflow: visible;
  }

  .course-button {
    min-height: 136px;
    grid-template-columns: 44px minmax(0, 1fr);
  }

  .course-arrow,
  .complete-mark {
    display: none;
  }

  .course-panel-note {
    display: none;
  }

  .scene-copy {
    grid-template-columns: 130px minmax(0, 1fr);
  }

  .teacher-line {
    grid-column: 1 / -1;
  }

  .animation-panel {
    align-items: flex-start;
  }

  .animation-actions {
    flex-wrap: wrap;
    justify-content: flex-end;
  }

  .ten-frame-scene,
  .base-ten-scene {
    grid-template-columns: 1fr 1fr;
  }

  .quantity-card,
  .exchange-arrow {
    display: none;
  }

  .ten-board {
    grid-column: 1;
  }

  .incoming-tray {
    grid-column: 2;
  }

  .outside-result,
  .math-result-chip {
    grid-column: 1 / -1;
  }

  .base-ten-scene .base-group--tens {
    grid-column: 1;
  }

  .base-ten-scene .base-group--ones {
    grid-column: 2;
  }

  .quantity-conservation {
    grid-column: 1 / -1;
  }
}

@media (max-width: 680px) {
  .five-frame-scene,
  .addition-machine-scene,
  .thousand-blocks-scene,
  .tenths-lab-scene,
  .decimal-compare-scene {
    grid-template-columns: 1fr;
  }

  .five-board { padding: 8px; gap: 4px; }
  .five-cell { min-height: 64px; }
  .five-reading { width: 100%; }

  .join-parts { grid-template-columns: 1fr 42px 1fr; }
  .join-part { min-height: 165px; padding: 10px 6px; }
  .join-token { width: 25px; }
  .join-whole { min-height: 130px; }
  .join-equation { grid-column: 1; }

  .hundred-grid { grid-template-columns: repeat(5, minmax(42px, 1fr)); width: 100%; }
  .hundred-flat { width: 100%; height: 55px; }
  .thousand-exchange { grid-template-columns: 1fr auto 1fr; }
  .thousand-equivalence,
  .thousand-blocks-scene .model-actions { grid-column: 1; }

  .place-value-scene--extended .place-table { min-width: 510px; overflow: visible; }
  .place-value-scene--extended { overflow-x: auto; padding-bottom: 6px; }

  .metric-ruler-scene { overflow-x: auto; }
  .ruler-wrap,
  .metric-ruler { min-width: 0; }
  .metric-reading { position: sticky; left: 0; }

  .tenths-board { width: 100%; min-width: 0; }
  .tenths-lab-scene { overflow: visible; }
  .whole-one-label,
  .tenths-equivalence,
  .tenths-lab-scene .model-actions { grid-column: 1; position: sticky; left: 0; }

  .decimal-compare-scene .compare-sign { justify-self: center; transform: rotate(90deg); }
  .decimal-compare-scene > p { grid-column: 1; }
  .decimal-number-line { overflow: visible; }
  .decimal-line-track { min-width: 0; padding-right: 4px; padding-left: 4px; }
  .clock-pair-scene { grid-template-columns:1fr; }
  .clock-pair-orbit { width:180px; min-height:180px; justify-self:center; }
  .clock-pair-scene p { grid-column:1; }

  .topbar,
  .page-shell {
    width: min(100% - 24px, 1380px);
  }

  .topbar {
    min-height: 70px;
  }

  .brand-mark {
    width: 40px;
    height: 40px;
    border-radius: 13px;
  }

  .brand-mark svg {
    width: 29px;
  }

  .brand-copy strong {
    font-size: 15px;
  }

  .brand-copy small,
  .topbar-status {
    display: none;
  }

  .progress-link {
    min-height: 40px;
    padding: 7px 10px;
    font-size: 11px;
  }

  .intro {
    padding: 34px 2px 22px;
  }

  .intro h1 {
    font-size: clamp(34px, 10vw, 47px);
  }

  .intro-copy {
    padding-left: 14px;
    font-size: 13px;
  }

  .course-panel {
    padding: 15px;
    border-radius: 22px;
  }

  .grade-filter button {
    min-height: 44px;
    font-size: 11px;
  }

  .course-list {
    grid-template-columns: 1fr;
  }

  .course-panel-toggle {
    min-height: 44px;
    padding: 8px 10px;
    display: inline-flex;
    align-items: center;
    color: var(--teal-dark);
    background: white;
    border: 1px solid #cfe1d8;
    border-radius: 9px;
    font-size: 10px;
    font-weight: 850;
    cursor: pointer;
  }

  .course-list:not(.is-mobile-open) .course-button:not(.is-active) {
    display: none;
  }

  .course-button {
    min-height: 94px;
    grid-template-columns: 44px minmax(0, 1fr) 20px;
  }

  .course-arrow,
  .complete-mark {
    display: grid;
  }

  .lesson-runtime {
    min-height: 760px;
    border-radius: 25px;
  }

  .lesson-header {
    min-height: 158px;
    padding: 20px 18px;
    align-items: flex-start;
    flex-direction: column;
    gap: 16px;
  }

  .lesson-progress-wrap {
    width: 100%;
    flex-basis: auto;
  }

  .readiness-card {
    margin: 12px 12px 0;
  }

  .readiness-toggle {
    min-height: 66px;
    grid-template-columns: 38px minmax(0, 1fr) 22px;
  }

  .readiness-state {
    display: none;
  }

  .readiness-details {
    padding: 0 12px 14px;
  }

  .readiness-details ul {
    grid-template-columns: 1fr;
  }

  .readiness-suggestion {
    align-items: stretch;
    flex-direction: column;
  }

  .scene-nav {
    padding: 12px;
  }

  .scene-step {
    min-width: 66px;
  }

  .scene-card {
    padding: 18px 12px 16px;
  }

  .scene-copy {
    min-height: 0;
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .phase-badge {
    width: fit-content;
  }

  .teacher-line {
    grid-column: 1;
    min-height: 62px;
  }

  .math-stage {
    min-height: 390px;
    padding: 14px 0;
  }

  .model-frame {
    min-height: 360px;
    padding: 42px 12px 20px;
    border-radius: 21px;
  }

  .scene-evidence {
    align-items: flex-start;
  }

  .animation-panel {
    padding: 13px;
    display: grid;
    gap: 12px;
  }

  .animation-actions {
    justify-content: stretch;
  }

  .animation-actions .control-button {
    flex: 1;
  }

  .speed-control {
    width: 100%;
    justify-content: space-between;
  }

  .runtime-footer {
    padding: 12px;
    grid-template-columns: 1fr 1fr;
  }

  .footer-note {
    display: none;
  }

  .runtime-footer .control-button {
    width: 100%;
  }

  .ten-frame-scene,
  .base-ten-scene {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .ten-board,
  .incoming-tray,
  .base-ten-scene .base-group--tens,
  .base-ten-scene .base-group--ones,
  .quantity-conservation,
  .ten-frame-scene .model-actions,
  .base-ten-scene .model-actions {
    grid-column: 1;
  }

  .ten-board {
    width: 100%;
    grid-template-columns: repeat(5, minmax(38px, 1fr));
    padding: 8px;
    gap: 4px;
  }

  .incoming-tray {
    min-height: 100px;
    border-radius: 18px;
  }

  .tray-tokens {
    min-height: 45px;
  }

  .base-group {
    min-height: 170px;
  }

  .rod-list,
  .cube-list {
    min-height: 90px;
  }

  .ten-rod {
    height: 92px;
  }

  .place-table {
    border-radius: 16px;
  }

  .place-column {
    min-height: 210px;
  }

  .place-content {
    padding: 12px 6px;
  }

  .array-scene {
    grid-template-columns: 42px minmax(220px, 1fr);
    gap: 8px;
    overflow-x: auto;
  }

  .array-dim--columns {
    grid-column: 2;
  }

  .array-equation,
  .array-scene .model-actions {
    grid-column: 1 / -1;
  }

  .array-board {
    min-height: 210px;
    padding: 12px;
    gap: 6px;
  }

  .comparison-scene {
    grid-template-columns: 1fr 45px 1fr;
    gap: 8px;
  }

  .compare-sign {
    width: 43px;
    height: 43px;
    border-radius: 13px;
    font-size: 24px;
  }

  .answer-grid {
    grid-template-columns: 1fr;
  }

  .model-actions {
    width: 100%;
    flex-wrap: wrap;
  }

  .model-actions .math-action {
    flex: 1 1 150px;
  }
}

@media (max-width: 680px) {
  .double-ten-scene,
  .subtraction-scene,
  .clock-scene,
  .shape-measure-scene,
  .sharing-scene {
    grid-template-columns: 1fr;
  }

  .double-ten-board,
  .take-board {
    grid-template-columns: repeat(5, minmax(34px, 1fr));
  }

  .double-ten-summary,
  .subtraction-status,
  .measure-reading {
    width: 100%;
  }

  .subtraction-scene .bridge-parts,
  .subtraction-scene .model-actions,
  .clock-scene .model-actions,
  .sharing-scene .fair-result,
  .sharing-scene .model-actions,
  .shape-measure-scene > p {
    grid-column: 1;
  }

  .object-row {
    grid-template-columns: 54px minmax(0, 1fr) 36px;
    padding: 11px;
  }

  .object-row i { width: 24px; }

  .split-array-scene {
    grid-template-columns: 46px minmax(250px, 1fr);
    overflow-x: auto;
  }

  .split-array-board { min-height: 180px; }
  .split-total { position: sticky; left: 52px; }

  .sharing-scene { justify-items: stretch; }
  .share-tray { width: 110px; justify-self: center; }
  .share-plates { grid-template-columns: repeat(2, minmax(110px, 1fr)); }

  .clock-face { width: 220px; }
  .clock-face > span { transform: rotate(var(--angle)) translateY(-82px) rotate(calc(var(--angle) * -1)); }
  .time-journey { padding: 15px 10px; }

  .symmetry-board { min-height: 220px; padding: 15px 8px; }
  .shape-half i { width: 54px; }

  .property-choice { grid-template-columns: 1fr 1fr; }
  .property-card { min-height: 100px; }
  .measure-rectangle { min-height: 210px; }

  .chart-plot { padding-right: 8px; padding-left: 34px; gap: 6px; }
  .data-bar { width: min(54px, 88%); }

  .fraction-bar-row { grid-template-columns: 1fr 44px; gap: 8px; }
  .fraction-bar-row > span { grid-column: 1 / -1; }
  .fraction-whole { min-width: 245px; height: 66px; }
  .fraction-compare-scene { grid-template-columns: 1fr; }
  .fraction-compare-scene .compare-sign { justify-self: center; transform: rotate(90deg); }
  .fraction-compare-scene > p { grid-column: 1; }

  .label-line-track { padding: 0 5px; }
  .label-line-track::before { right: 5px; left: 5px; }
  .label-tick { min-width: 44px; }
}

@media (max-width: 390px) {
  .ten-board {
    grid-template-columns: repeat(5, minmax(33px, 1fr));
  }

  .counter {
    width: 27px;
  }

  .control-button {
    padding-right: 10px;
    padding-left: 10px;
    font-size: 12px;
  }

  .array-board {
    min-width: 230px;
  }
}

@media (max-width: 680px) {
  .direct-check-actions {
    align-items: stretch;
    flex-direction: column-reverse;
  }

  .direct-check-actions .control-button {
    width: 100%;
  }

  .tiered-hint {
    grid-template-columns: 1fr;
  }

  .axis-choice {
    grid-template-columns: 1fr;
  }

  .shape-challenge-scene--direct {
    grid-template-columns: 1fr;
  }

  .direct-property-choice {
    grid-template-columns: 1fr 1fr;
  }

  .fraction-choice {
    grid-template-columns: 1fr 44px;
  }

  .fraction-choice > span {
    grid-column: 1 / -1;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

/* Expansion batch 2: foundational number and fraction models */
.bead-rack-scene,
.pattern-strip-scene,
.pairing-counter-scene,
.rounding-line-scene,
.hundreds-model-scene,
.subtraction-regroup-scene,
.ten-thousand-scene {
  width: min(100%, 860px);
}

.bead-rack-scene { display: grid; grid-template-columns: minmax(320px, 1fr) 170px; gap: 22px; align-items: center; }
.bead-rail { min-height: 150px; padding: 28px 24px; position: relative; display: flex; align-items: center; gap: 7px; background: linear-gradient(145deg, #fff, var(--teal-pale)); border: 2px solid #acd8d5; border-radius: 24px; box-shadow: inset 0 -9px 0 rgba(14,138,156,.06); }
.bead-rail::before { content: ''; height: 7px; position: absolute; right: 20px; left: 20px; background: var(--ink-soft); border-radius: 999px; }
.rack-bead { min-width: 34px; aspect-ratio: 1; z-index: 1; display: grid; place-items: center; opacity: .22; transform: translateY(12px) scale(.82); transition: opacity 900ms ease, transform 1200ms var(--ease-out); }
.rack-bead i { width: 100%; height: 100%; display: block; background: white; border: 3px solid var(--teal-dark); border-radius: 50%; }
.rack-bead.is-active { opacity: 1; transform: none; }
.rack-bead.is-active.is-first-five i { background: var(--blue); border-color: var(--blue-dark); }
.rack-bead.is-active.is-second-five i { background: var(--orange); border-color: var(--orange-dark); }
.rack-reading { padding: 18px; display: grid; gap: 3px; background: white; border: 1px solid var(--line); border-radius: 19px; text-align: center; }
.rack-reading strong { color: var(--teal-dark); font-size: 38px; }
.rack-reading small { color: var(--ink-soft); font-weight: 800; }

.pattern-strip-scene { display: grid; gap: 15px; }
.pattern-strip { padding: 20px; display: grid; grid-template-columns: repeat(5, 1fr); gap: 12px; background: linear-gradient(135deg, var(--violet-pale), white); border: 2px solid #d2c7ed; border-radius: 24px; }
.pattern-strip > span { min-height: 92px; display: grid; place-items: center; align-content: center; gap: 3px; background: white; border: 2px solid #c9b9e8; border-radius: 18px; box-shadow: 0 6px 0 rgba(83,55,151,.08); animation: sentence-in 900ms var(--ease-out) var(--delay) both; }
.pattern-strip strong { color: var(--violet-dark); font-size: 29px; }
.pattern-strip small { color: var(--ink-soft); font-size: 10px; font-weight: 850; }
.pattern-strip-scene p { margin: 0; color: var(--ink-soft); text-align: center; font-weight: 800; }
.equal-groups-placeholder { min-height: 120px; grid-column: 1 / -1; display: grid; place-items: center; color: var(--ink-soft); background: white; border: 2px dashed #b9d8d4; border-radius: 18px; font-weight: 800; }
.groups-remainder { grid-column: 1 / -1; justify-self: center; padding: 7px 12px; color: var(--orange-dark); background: var(--orange-pale); border-radius: 11px; font-weight: 800; }
.groups-remainder strong { font-size: 20px; }

.bond-fact-family { width: min(100%, 420px); margin-top: 16px; display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.bond-fact-family span { min-height: 46px; padding: 8px 10px; display: grid; place-items: center; color: var(--blue-dark); background: white; border: 1px solid #bad0f5; border-radius: 12px; font-weight: 900; animation: sentence-in 1000ms var(--ease-out) both; }
.number-bond-scene .model-actions { width: 100%; margin-top: 16px; flex-wrap: wrap; }
.number-bond-scene.is-composed .bond-whole { box-shadow: 0 0 0 6px rgba(22,132,91,.1); transform: scale(1.04); transition: transform 900ms var(--ease-out), box-shadow 900ms ease; }

.pairing-board { padding: 18px; display: grid; grid-template-columns: repeat(4, minmax(72px, 1fr)); gap: 12px; background: white; border: 2px solid #c7d9d4; border-radius: 24px; }
.pairing-token { min-height: 88px; display: grid; place-items: center; align-content: center; gap: 4px; background: #f6f8f6; border: 2px dashed #cbd6d0; border-radius: 18px; transition: background 900ms ease, border-color 900ms ease, transform 1000ms var(--ease-out); }
.pairing-token i { width: 38px; aspect-ratio: 1; display: block; background: var(--orange); border: 3px solid var(--orange-dark); border-radius: 50%; box-shadow: inset -4px -4px 0 rgba(169,77,16,.14); }
.pairing-token small { color: var(--ink-soft); font-size: 9px; font-weight: 800; }
.pairing-token.is-paired { background: var(--teal-pale); border-style: solid; border-color: #9ccfcc; transform: translateY(-3px); }
.pairing-token.is-paired:nth-child(4n+1),
.pairing-token.is-paired:nth-child(4n+2) { background: var(--blue-pale); border-color: #b5c9ef; }
.pairing-reading { margin: 14px auto; padding: 10px 16px; display: flex; align-items: center; justify-content: center; gap: 10px; background: var(--green-pale); border: 1px solid #c2e0ce; border-radius: 15px; }
.pairing-reading strong { color: var(--green-dark); font-size: 23px; }
.pairing-reading small { color: var(--ink-soft); font-weight: 800; }
.pairing-counter-scene .model-actions { flex-wrap: wrap; }

.rounding-line-scene { display: grid; gap: 16px; }
.rounding-track { min-height: 150px; position: relative; background: linear-gradient(180deg, white, #f7f9f7); border: 1px solid var(--line); border-radius: 22px; }
.rounding-track::before { content: ''; height: 6px; position: absolute; right: 36px; left: 36px; top: 72px; background: linear-gradient(90deg, var(--teal), var(--blue)); border-radius: 999px; }
.rounding-end,
.rounding-mid,
.rounding-point { position: absolute; top: 49px; display: grid; justify-items: center; gap: 5px; transform: translateX(-50%); }
.rounding-end--left { left: 36px; transform: none; }
.rounding-end--right { right: 36px; transform: none; }
.rounding-mid,
.rounding-point { left: var(--position); }
.rounding-end i,
.rounding-mid i { width: 4px; height: 34px; background: var(--teal-dark); border-radius: 999px; }
.rounding-point { top: 28px; z-index: 2; color: var(--orange-dark); transition: left 1700ms var(--ease-out); }
.rounding-point i { width: 22px; aspect-ratio: 1; background: var(--yellow); border: 4px solid var(--orange); border-radius: 50%; box-shadow: 0 0 0 7px rgba(242,140,40,.13); }
.rounding-end strong,
.rounding-mid strong,
.rounding-point strong { padding: 4px 8px; background: white; border: 1px solid var(--line); border-radius: 8px; font-size: 12px; }
.rounding-mid small { color: var(--ink-soft); font-size: 9px; font-weight: 850; }
.rounding-distance { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.rounding-distance span { min-height: 46px; padding: 8px 12px; display: grid; place-items: center; color: var(--blue-dark); background: var(--blue-pale); border-radius: 13px; font-weight: 850; }
.rounding-result { width: fit-content; min-width: 230px; margin: auto; padding: 12px 20px; display: grid; grid-template-columns: auto auto; gap: 2px 12px; align-items: center; background: var(--orange-pale); border: 1px solid #eac49c; border-radius: 16px; }
.rounding-result strong { color: var(--orange-dark); font-size: 28px; }
.rounding-result small { grid-column: 1 / -1; color: var(--ink-soft); text-align: center; }

.hundreds-model-scene { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.hundreds-place-group { min-height: 220px; padding: 14px; display: grid; grid-template-rows: auto 1fr auto; gap: 9px; background: white; border: 2px solid var(--line); border-radius: 22px; text-align: center; }
.hundreds-place-group > span { padding: 4px 8px; color: white; background: var(--violet); border-radius: 8px; font-size: 11px; font-weight: 900; }
.hundreds-place-group:nth-child(2) > span { background: var(--orange); }
.hundreds-place-group:nth-child(3) > span { background: var(--blue); }
.hundreds-place-group > div { display: flex; flex-wrap: wrap; align-content: center; justify-content: center; gap: 6px; }
.hundred-model-flat { width: 50px; height: 58px; background: repeating-linear-gradient(0deg,#c8b9eb 0 5px,#f0ebff 5px 6px); border: 2px solid var(--violet-dark); border-radius: 7px; }
.hundred-model-rod { width: 13px; height: 62px; background: repeating-linear-gradient(0deg,var(--orange) 0 5px,#ffd9ad 5px 6px); border: 2px solid var(--orange-dark); border-radius: 5px; }
.hundred-model-one { width: 24px; aspect-ratio: 1; background: var(--blue); border: 2px solid var(--blue-dark); border-radius: 6px; }
.hundreds-model-total { grid-column: 1 / -1; justify-self: center; padding: 10px 18px; display: flex; align-items: center; gap: 12px; background: var(--teal-pale); border: 1px solid #b5dcda; border-radius: 15px; }
.hundreds-model-total strong { color: var(--teal-dark); font-size: 26px; }
.hundreds-model-total small { color: var(--ink-soft); font-weight: 800; }

.subtraction-regroup-scene { display: grid; grid-template-columns: 1fr 110px 1fr; gap: 16px; align-items: center; }
.regroup-column { min-height: 240px; padding: 16px; display: grid; grid-template-rows: auto 1fr auto; gap: 10px; background: white; border: 2px solid var(--line); border-radius: 23px; text-align: center; }
.regroup-column > span { padding: 5px 9px; color: white; background: var(--orange); border-radius: 9px; font-size: 11px; font-weight: 900; }
.regroup-column:nth-of-type(3) > span { background: var(--blue); }
.regroup-column > div { display: flex; flex-wrap: wrap; justify-content: center; align-content: center; gap: 5px; }
.regroup-ten { width: 18px; height: 90px; background: repeating-linear-gradient(0deg,var(--orange) 0 7px,#ffd9ad 7px 9px); border: 2px solid var(--orange-dark); border-radius: 6px; }
.regroup-one { width: 28px; aspect-ratio: 1; background: var(--blue); border: 2px solid var(--blue-dark); border-radius: 7px; transition: opacity 900ms ease, transform 900ms var(--ease-out); }
.regroup-one.is-removed { opacity: .18; transform: translateY(14px) scale(.8); }
.regroup-exchange { display: grid; place-items: center; gap: 5px; color: var(--ink-soft); text-align: center; font-size: 10px; font-weight: 850; }
.regroup-exchange b { color: var(--orange); font-size: 38px; }
.regroup-result { grid-column: 1 / -1; justify-self: center; padding: 11px 18px; display: flex; align-items: center; gap: 12px; background: var(--green-pale); border: 1px solid #c2e0ce; border-radius: 15px; }
.regroup-result strong { color: var(--green-dark); font-size: 27px; }
.regroup-result small { color: var(--ink-soft); }
.subtraction-regroup-scene .model-actions { grid-column: 1 / -1; flex-wrap: wrap; }

.ten-thousand-scene { display: grid; grid-template-columns: minmax(310px, 1.2fr) 100px minmax(210px, .8fr); gap: 17px; align-items: center; }
.thousand-unit-list,
.ten-thousand-unit-wrap { min-height: 250px; padding: 17px; display: grid; align-content: center; justify-items: center; gap: 10px; background: white; border: 2px solid #cbbdeb; border-radius: 23px; }
.thousand-unit-list > div { display: grid; grid-template-columns: repeat(5, minmax(42px, 1fr)); gap: 7px; }
.thousand-unit { min-height: 62px; display: grid; place-items: center; background: linear-gradient(145deg,var(--violet),#5a3e9f); border: 2px solid var(--violet-dark); border-radius: 9px; box-shadow: 4px 5px 0 rgba(83,55,151,.11); }
.thousand-unit.is-selected { background: var(--yellow); border-color: #8a5d00; }
.thousand-unit small { padding: 2px 4px; color: var(--violet-dark); background: white; border-radius: 5px; font-size: 8px; font-weight: 900; }
.ten-thousand-arrow { display: grid; place-items: center; color: var(--ink-soft); text-align: center; font-size: 10px; font-weight: 850; }
.ten-thousand-arrow b { color: var(--violet); font-size: 42px; }
.ten-thousand-unit { width: 170px; aspect-ratio: 1; display: grid; place-items: center; background: linear-gradient(145deg,#9b81dc,var(--violet)); border: 4px solid var(--violet-dark); border-radius: 25px; box-shadow: inset -20px -20px 0 rgba(83,55,151,.15), 12px 14px 0 rgba(83,55,151,.11); animation: thousand-arrive 1900ms var(--ease-out) both; }
.ten-thousand-unit b { padding: 5px 9px; color: var(--violet-dark); background: white; border-radius: 9px; }
.ten-thousand-result { grid-column: 1 / -1; justify-self: center; padding: 10px 17px; display: flex; align-items: center; gap: 10px; background: var(--green-pale); border-radius: 15px; }
.ten-thousand-result strong { color: var(--green-dark); font-size: 21px; }
.ten-thousand-result small { color: var(--ink-soft); }
.ten-thousand-scene .model-actions { grid-column: 1 / -1; }

.place-value-scene--extended .place-column--tenThousands .place-heading { color: white; background: var(--violet); }
.place-unit--tenThousands { width: 52px; background: linear-gradient(145deg,#9b81dc,var(--violet)); border-color: var(--violet-dark); }
.place-value-scene--extended .model-actions { justify-self: center; flex-wrap: wrap; }
.partition-shape i.is-irregular-part { flex: 1.6; transform: skewX(-8deg); }
.fraction-shape-scene.is-irregular .partition-shape > div { grid-template-columns: 1fr 1fr .7fr 1.3fr; }

@media (max-width: 680px) {
  .bead-rack-scene,
  .subtraction-regroup-scene,
  .ten-thousand-scene { grid-template-columns: 1fr; }
  .bead-rail { padding: 22px 12px; gap: 3px; }
  .rack-bead { min-width: 26px; }
  .pattern-strip { padding: 12px; gap: 6px; }
  .pattern-strip > span { min-height: 72px; }
  .pattern-strip strong { font-size: 22px; }
  .pairing-board { grid-template-columns: repeat(2, minmax(88px, 1fr)); padding: 12px; }
  .rounding-track::before { right: 20px; left: 20px; }
  .rounding-end--left { left: 20px; }
  .rounding-end--right { right: 20px; }
  .hundreds-model-scene { grid-template-columns: repeat(3, minmax(105px, 1fr)); overflow-x: auto; }
  .hundreds-place-group { min-height: 190px; padding: 9px; }
  .subtraction-regroup-scene .regroup-result,
  .subtraction-regroup-scene .model-actions,
  .ten-thousand-result,
  .ten-thousand-scene .model-actions { grid-column: 1; }
  .regroup-exchange { grid-template-columns: 1fr auto 1fr; }
  .thousand-unit-list > div { width: 100%; }
  .ten-thousand-arrow { grid-template-columns: 1fr auto 1fr; }
  .bond-fact-family { grid-template-columns: 1fr; }
  .rounding-distance { gap: 6px; }
  .place-value-scene--extended .model-actions { position: sticky; left: 0; }
}

/* Final course system: semantic transitions, balance and calendar */
.semantic-trail {
  width: min(100%, 860px);
  margin-top: 22px;
  padding: 20px;
  position: relative;
  display: grid;
  gap: 14px;
  overflow: hidden;
  background: linear-gradient(145deg, rgba(255,255,255,.96), rgba(232,247,245,.92));
  border: 1px solid #b9d8d4;
  border-radius: 24px;
  box-shadow: 0 12px 30px rgba(31,65,71,.08);
}
.semantic-trail::before { content: '数学证据'; position: absolute; right: 17px; top: 12px; color: var(--teal-dark); font-size: 10px; font-weight: 900; letter-spacing: .08em; }
.semantic-trail__line { height: 7px; margin: 8px 25px -3px; overflow: hidden; background: #dce7e3; border-radius: 999px; }
.semantic-trail__line i { width: calc(var(--trail-progress) / 3 * 100%); height: 100%; display: block; background: linear-gradient(90deg, var(--teal), var(--blue), var(--violet)); border-radius: inherit; transition: width 1500ms var(--ease-out); }
.semantic-trail ol { margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; list-style: none; }
.semantic-trail li { min-height: 116px; padding: 16px 13px; display: grid; grid-template-rows: auto 1fr; gap: 8px; align-items: start; opacity: .38; background: #f5f7f6; border: 2px dashed #cbd8d4; border-radius: 18px; transform: translateY(8px) scale(.97); transition: opacity 1100ms ease, transform 1400ms var(--ease-out), background 900ms ease, border-color 900ms ease, box-shadow 900ms ease; }
.semantic-trail li > span { width: 30px; aspect-ratio: 1; display: grid; place-items: center; color: var(--ink-soft); background: white; border: 1px solid var(--line); border-radius: 50%; font-weight: 950; }
.semantic-trail li strong { color: var(--ink-soft); font-size: 14px; line-height: 1.55; }
.semantic-trail li.is-visible { opacity: 1; background: white; border-style: solid; border-color: #9bcfca; transform: none; }
.semantic-trail li.is-visible > span { color: white; background: var(--teal); border-color: var(--teal-dark); }
.semantic-trail li.is-current { border-color: var(--blue); box-shadow: 0 0 0 5px rgba(58,110,184,.1), 0 10px 22px rgba(58,110,184,.11); }
.semantic-trail li.is-current > span { background: var(--blue); border-color: var(--blue-dark); animation: semantic-step-pulse 1800ms ease-in-out infinite; }
.semantic-trail__action { justify-self: center; min-width: 180px; }
.semantic-trail__result { margin: 0; padding: 10px 14px; display: flex; align-items: center; justify-content: center; gap: 9px; color: var(--green-dark); background: var(--green-pale); border: 1px solid #b8ddc7; border-radius: 14px; font-weight: 900; animation: sentence-in 1200ms var(--ease-out) both; }
.semantic-trail__result span { width: 25px; aspect-ratio: 1; display: grid; place-items: center; color: white; background: var(--green-dark); border-radius: 50%; }
@keyframes semantic-step-pulse { 50% { box-shadow: 0 0 0 8px rgba(58,110,184,.12); transform: scale(1.04); } }

.balance-scale-scene,
.calendar-board-scene { width: min(100%, 760px); }
.balance-scale-scene { display: grid; justify-items: center; gap: 15px; }
.balance-question { padding: 11px 18px; display: grid; gap: 2px; justify-items: center; background: white; border: 1px solid var(--line); border-radius: 15px; }
.balance-question span { color: var(--ink-soft); font-size: 11px; font-weight: 850; }
.balance-question strong { color: var(--teal-dark); font-size: 22px; }
.balance-question b { padding: 0 8px; color: var(--orange-dark); font-size: 27px; }
.balance-scale { width: min(100%, 620px); min-height: 320px; position: relative; filter: drop-shadow(0 16px 13px rgba(31,65,71,.12)); }
.balance-beam { width: 76%; height: 16px; position: absolute; left: 12%; top: 76px; z-index: 3; background: linear-gradient(180deg,#5e7b79,#294846); border-radius: 999px; transform: rotate(var(--balance-tilt)); transform-origin: center; transition: transform 1800ms var(--ease-out); }
.balance-beam > span { width: 28px; aspect-ratio: 1; position: absolute; left: 50%; top: 50%; background: var(--yellow); border: 5px solid #8a5d00; border-radius: 50%; transform: translate(-50%,-50%); }
.balance-beam > i { width: 8px; height: 135px; position: absolute; left: 50%; top: 5px; background: #456866; transform: translateX(-50%); }
.balance-pan { width: 34%; min-height: 120px; padding: 14px 10px 9px; position: absolute; top: 98px; z-index: 2; display: grid; grid-template-rows: 1fr auto; align-items: end; background: rgba(255,255,255,.96); border: 3px solid #708b89; border-radius: 18px 18px 45% 45%; transition: transform 1800ms var(--ease-out); }
.balance-pan::before,.balance-pan::after { content: ''; width: 3px; height: 62px; position: absolute; top: -64px; background: #708b89; transform-origin: bottom; }
.balance-pan::before { left: 20%; transform: rotate(13deg); }.balance-pan::after { right: 20%; transform: rotate(-13deg); }
.balance-pan--left { left: 3%; transform: translateY(var(--left-shift)); }
.balance-pan--right { right: 3%; transform: translateY(var(--right-shift)); }
.balance-pan > div { display: flex; flex-wrap: wrap-reverse; justify-content: center; gap: 4px; }
.balance-pan strong { color: var(--ink); font-size: 22px; text-align: center; }
.balance-weight { width: 25px; height: 32px; display: block; background: var(--teal); border: 2px solid var(--teal-dark); border-radius: 7px 7px 4px 4px; box-shadow: inset -4px -4px 0 rgba(0,0,0,.09); animation: sentence-in 1100ms var(--ease-out) calc(var(--weight-index) * 80ms) both; }
.balance-weight--orange { background: var(--orange); border-color: var(--orange-dark); }
.balance-stand { width: 46%; height: 185px; position: absolute; left: 27%; bottom: 0; display: grid; justify-items: center; align-items: end; }
.balance-stand i { width: 26px; height: 170px; display: block; background: linear-gradient(90deg,#456866,#779593,#456866); clip-path: polygon(40% 0,60% 0,75% 85%,25% 85%); }
.balance-stand span { width: 100%; height: 24px; position: absolute; bottom: 0; background: #395b59; border-radius: 50% 50% 12px 12px; }
.balance-scale-scene > p,.calendar-board-scene > p { margin: 0; color: var(--ink-soft); text-align: center; font-weight: 850; }

.calendar-board-scene { padding: 22px; display: grid; gap: 10px; background: linear-gradient(150deg,#fff,var(--blue-pale)); border: 2px solid #c1d1ed; border-radius: 26px; box-shadow: 0 16px 38px rgba(58,110,184,.1); }
.calendar-heading { padding: 4px 4px 13px; display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 10px; border-bottom: 2px dashed #c2d0e9; }
.calendar-heading span { color: var(--ink-soft); font-weight: 850; }.calendar-heading strong { color: var(--blue-dark); font-size: 28px; }.calendar-heading small { color: var(--ink-soft); font-weight: 800; }
.calendar-week,.calendar-grid { display: grid; grid-template-columns: repeat(7,1fr); gap: 7px; }
.calendar-week span { min-height: 32px; display: grid; place-items: center; color: var(--blue-dark); font-size: 11px; font-weight: 950; }
.calendar-grid > span { min-height: 57px; position: relative; display: grid; place-items: center; background: rgba(255,255,255,.88); border: 1px solid #d4ddea; border-radius: 13px; }
.calendar-grid > span:nth-child(7n+1),.calendar-grid > span:nth-child(7n) { background: #fff8ee; }
.calendar-grid b { z-index: 1; color: var(--ink); font-size: 16px; }
.calendar-grid .is-empty { opacity: .28; background: transparent; border-style: dashed; }
.calendar-grid .is-highlighted { border-color: var(--orange); box-shadow: 0 6px 13px rgba(242,140,40,.15); animation: sentence-in 1300ms var(--ease-out) both; }
.calendar-grid .is-highlighted i { width: 38px; aspect-ratio: 1; position: absolute; border: 3px solid var(--orange); border-radius: 49% 55% 48% 53%; transform: rotate(-8deg); }

@media (max-width: 680px) {
  .semantic-trail { padding: 16px 12px; }
  .semantic-trail ol { grid-template-columns: 1fr; }
  .semantic-trail li { min-height: 74px; grid-template-columns: 34px 1fr; grid-template-rows: 1fr; align-items: center; }
  .semantic-trail__line { display: none; }
  .balance-scale { min-height: 270px; transform: scale(.91); transform-origin: top center; margin-bottom: -25px; }
  .calendar-board-scene { padding: 14px 9px; }
  .calendar-heading { grid-template-columns: auto 1fr; }
  .calendar-heading small { grid-column: 1 / -1; }
  .calendar-week,.calendar-grid { gap: 4px; }
  .calendar-grid > span { min-height: 44px; border-radius: 10px; }
  .calendar-grid .is-highlighted i { width: 31px; }
}