:root {
  --ml-serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --ml-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --ml-math: "STIX Two Math", "Cambria Math", "Times New Roman", serif;
  --ml-cinnabar: var(--accent);
  --ml-gold: var(--gold);
  --ml-panel: color-mix(in srgb, var(--surface) 92%, transparent);
  --ml-panel-strong: color-mix(in srgb, var(--surface-strong) 96%, transparent);
  --ml-control: color-mix(in srgb, var(--bg) 78%, transparent);
  --ml-radius: 2px;
}

.math-learning-page {
  min-width: 320px;
  background:
    radial-gradient(circle at 82% 12%, color-mix(in srgb, var(--accent) 9%, transparent), transparent 26rem),
    var(--bg);
  font-family: var(--ml-sans);
}

.math-learning-page .site-header {
  font-family: var(--ml-sans);
}

.math-learning-page .brand-name {
  font-family: var(--ml-serif);
  letter-spacing: 0.02em;
}

.math-learning-page .brand-seal {
  font-family: var(--ml-serif);
}

.math-learning-page .theme-toggle {
  font-family: var(--ml-serif);
}

.ml-shell {
  width: var(--page);
  margin: 0 auto;
}

.ml-fixed-tools {
  position: fixed;
  top: 88px;
  left: max(18px, calc((100vw - 1340px) / 2));
  right: max(18px, calc((100vw - 1340px) / 2));
  z-index: 8;
  display: flex;
  justify-content: space-between;
  pointer-events: none;
}

.ml-tool {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 9px 14px;
  border: 1px solid var(--line-strong);
  border-radius: var(--ml-radius);
  background: var(--ml-control);
  color: var(--text);
  font-size: 13px;
  font-weight: 700;
  white-space: nowrap;
  cursor: pointer;
  pointer-events: auto;
  -webkit-backdrop-filter: blur(16px);
  backdrop-filter: blur(16px);
  transition: border-color 180ms ease, color 180ms ease, transform 180ms var(--ease);
}

.ml-tool:hover,
.ml-tool:focus-visible {
  border-color: var(--ml-cinnabar);
  color: var(--ml-cinnabar);
}

.ml-tool:active,
.ml-button:active,
.ml-choice:active,
.ml-preset:active,
.ml-course-link:active {
  transform: translateY(1px);
}

.ml-hub-hero,
.ml-lesson-hero {
  display: grid;
  grid-template-columns: minmax(300px, 0.78fr) minmax(520px, 1.22fr);
  gap: clamp(42px, 7vw, 104px);
  align-items: center;
  min-height: calc(100dvh - 70px);
  padding: clamp(82px, 10vh, 118px) 0 clamp(54px, 7vh, 84px);
}

.ml-lesson-hero {
  grid-template-columns: minmax(300px, 0.68fr) minmax(560px, 1.32fr);
}

.ml-kicker {
  margin: 0 0 20px;
  color: var(--ml-gold);
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.ml-hero-copy h1 {
  max-width: 9.5em;
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(52px, 6vw, 92px);
  font-weight: 600;
  letter-spacing: -0.055em;
  line-height: 0.98;
}

.ml-lesson-hero .ml-hero-copy h1 {
  max-width: 8.8em;
  font-size: clamp(46px, 5vw, 76px);
  line-height: 1.02;
}

.ml-hero-copy > p:not(.ml-kicker) {
  max-width: 25em;
  margin: 24px 0 0;
  color: var(--muted);
  font-family: var(--ml-serif);
  font-size: clamp(18px, 1.7vw, 23px);
  line-height: 1.65;
}

.ml-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.ml-button,
.ml-choice,
.ml-preset,
.ml-course-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  border: 1px solid var(--line-strong);
  border-radius: var(--ml-radius);
  background: transparent;
  color: var(--text);
  font: 700 13px/1 var(--ml-sans);
  white-space: nowrap;
  cursor: pointer;
  transition: background 180ms ease, border-color 180ms ease, color 180ms ease, transform 180ms var(--ease);
}

.ml-button,
.ml-course-link {
  padding: 0 18px;
}

.ml-button:hover,
.ml-button:focus-visible,
.ml-choice:hover,
.ml-choice:focus-visible,
.ml-preset:hover,
.ml-preset:focus-visible,
.ml-course-link:hover,
.ml-course-link:focus-visible {
  border-color: var(--ml-cinnabar);
  color: var(--ml-cinnabar);
}

.ml-button--primary,
.ml-course-link--primary {
  border-color: color-mix(in srgb, var(--ml-cinnabar) 88%, #101112);
  background: color-mix(in srgb, var(--ml-cinnabar) 88%, #101112);
  color: #fff7ee;
}

.ml-button--primary:hover,
.ml-button--primary:focus-visible,
.ml-course-link--primary:hover,
.ml-course-link--primary:focus-visible {
  background: color-mix(in srgb, var(--ml-cinnabar) 86%, var(--text));
  color: #fff7ee;
}

.ml-hero-visual {
  position: relative;
  overflow: hidden;
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--surface);
  box-shadow: 0 26px 90px var(--shadow);
  aspect-ratio: 16 / 9;
}

.ml-hero-visual img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.ml-hero-visual::after {
  position: absolute;
  inset: 0;
  border: 1px solid rgba(255, 255, 255, 0.08);
  content: "";
  pointer-events: none;
}

.ml-section {
  padding: clamp(80px, 11vw, 144px) 0;
  border-top: 1px solid var(--line);
}

.ml-section-heading {
  max-width: 720px;
  margin-bottom: clamp(34px, 5vw, 60px);
}

.ml-section-heading h2,
.ml-course-copy h2,
.ml-lesson-section h2 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(36px, 4.5vw, 62px);
  font-weight: 600;
  letter-spacing: -0.045em;
  line-height: 1.08;
}

.ml-section-heading p,
.ml-course-copy p,
.ml-lesson-section > p,
.ml-explanation p {
  color: var(--muted);
  font-family: var(--ml-serif);
  font-size: 18px;
  line-height: 1.75;
}

.ml-principles {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: clamp(28px, 6vw, 84px);
  align-items: start;
}

.ml-principle-copy {
  max-width: 700px;
}

.ml-principle-copy blockquote {
  margin: 0;
  padding-left: 24px;
  border-left: 3px solid var(--ml-cinnabar);
  font-family: var(--ml-serif);
  font-size: clamp(27px, 3.2vw, 44px);
  line-height: 1.35;
}

.ml-principle-notes {
  display: grid;
  gap: 24px;
}

.ml-principle-notes article {
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.ml-principle-notes h3,
.ml-course-copy h3,
.ml-lesson-section h3,
.ml-panel h2,
.ml-panel h3 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: 24px;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.ml-principle-notes p {
  margin: 10px 0 0;
  color: var(--muted);
  line-height: 1.7;
}

.ml-course-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.18fr) minmax(320px, 0.82fr);
  grid-template-rows: auto auto;
  gap: 22px;
}

.ml-course {
  display: grid;
  min-height: 320px;
  padding: clamp(28px, 4vw, 48px);
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--ml-panel);
}

.ml-course--algebra {
  grid-row: span 2;
  min-height: 664px;
  background:
    linear-gradient(155deg, color-mix(in srgb, var(--accent) 17%, transparent), transparent 42%),
    var(--ml-panel);
}

.ml-course--geometry {
  background:
    repeating-linear-gradient(135deg, transparent 0 30px, color-mix(in srgb, var(--text) 4%, transparent) 30px 31px),
    var(--ml-panel);
}

.ml-course--analysis {
  background:
    radial-gradient(ellipse at 88% 22%, color-mix(in srgb, var(--gold) 16%, transparent), transparent 45%),
    var(--ml-panel);
}

.ml-course-copy {
  display: grid;
  align-content: start;
}

.ml-course-copy p {
  max-width: 31em;
  margin: 16px 0 0;
}

.ml-course-link {
  width: max-content;
  margin-top: auto;
}

.ml-symbol {
  align-self: center;
  margin: clamp(34px, 8vw, 76px) 0;
  color: var(--text);
  font: 400 clamp(58px, 8vw, 118px)/1 var(--ml-math);
  letter-spacing: -0.04em;
}

.ml-course:not(.ml-course--algebra) .ml-symbol {
  margin: 28px 0;
  font-size: clamp(50px, 5vw, 76px);
}

.ml-method {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
}

.ml-method article {
  min-height: 220px;
  padding: 24px 0 0;
  border-top: 2px solid var(--line-strong);
}

.ml-method strong {
  display: block;
  font-family: var(--ml-serif);
  font-size: 28px;
  font-weight: 600;
}

.ml-method p {
  margin: 14px 0 0;
  color: var(--muted);
  line-height: 1.7;
}

.ml-path-map {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: clamp(30px, 7vw, 96px);
  align-items: start;
}

.ml-path-copy p {
  color: var(--muted);
  font-family: var(--ml-serif);
  font-size: 19px;
  line-height: 1.75;
}

.ml-path-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.ml-path-list article {
  min-height: 160px;
  padding: 24px;
  border: 1px solid var(--line);
  background: var(--ml-panel);
}

.ml-path-list strong {
  display: block;
  font-family: var(--ml-serif);
  font-size: 22px;
}

.ml-path-list p {
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.65;
}

.ml-lesson-stage {
  position: relative;
  min-height: 560px;
  padding: clamp(24px, 3vw, 38px);
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--ml-panel);
  box-shadow: 0 24px 80px var(--shadow);
}

.ml-stage-header {
  display: flex;
  justify-content: space-between;
  gap: 22px;
  align-items: start;
  margin-bottom: 28px;
}

.ml-stage-header p {
  max-width: 31em;
  margin: 10px 0 0;
  color: var(--muted);
  line-height: 1.6;
}

.ml-stage-header strong {
  display: block;
  font-family: var(--ml-serif);
  font-size: 28px;
}

.ml-stage-label {
  color: var(--ml-gold);
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.ml-equation {
  margin: 44px 0 24px;
  overflow-x: auto;
  color: var(--text);
  font: 400 clamp(42px, 6vw, 76px)/1.2 var(--ml-math);
  text-align: center;
  white-space: nowrap;
}

.ml-balance {
  position: relative;
  width: min(88%, 520px);
  height: 150px;
  margin: 0 auto 26px;
}

.ml-balance-beam {
  position: absolute;
  top: 34px;
  left: 5%;
  width: 90%;
  height: 3px;
  background: var(--text);
  transform: rotate(var(--balance-tilt, 0deg));
  transform-origin: center;
  transition: transform 360ms var(--ease);
}

.ml-balance-beam::before,
.ml-balance-beam::after {
  position: absolute;
  top: 3px;
  width: 1px;
  height: 58px;
  background: var(--line-strong);
  content: "";
}

.ml-balance-beam::before { left: 10%; }
.ml-balance-beam::after { right: 10%; }

.ml-balance-pan {
  position: absolute;
  top: 92px;
  width: 31%;
  padding: 8px 10px;
  border-top: 2px solid var(--ml-cinnabar);
  color: var(--muted);
  text-align: center;
}

.ml-balance-pan--left { left: 0; }
.ml-balance-pan--right { right: 0; }

.ml-balance-stand {
  position: absolute;
  top: 36px;
  left: calc(50% - 2px);
  width: 4px;
  height: 94px;
  background: var(--gold);
}

.ml-balance-stand::after {
  position: absolute;
  bottom: -3px;
  left: -42px;
  width: 88px;
  height: 3px;
  background: var(--gold);
  content: "";
}

.ml-controls {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

.ml-choice,
.ml-preset {
  min-height: 40px;
  padding: 0 13px;
  font-size: 12px;
}

.ml-choice[aria-pressed="true"],
.ml-preset[aria-pressed="true"] {
  border-color: var(--ml-cinnabar);
  background: color-mix(in srgb, var(--ml-cinnabar) 18%, transparent);
  color: var(--text);
}

.ml-feedback {
  min-height: 54px;
  margin: 22px 0 0;
  padding: 14px 16px;
  border-left: 3px solid var(--ml-cinnabar);
  background: color-mix(in srgb, var(--surface-strong) 72%, transparent);
  color: var(--muted);
  line-height: 1.6;
}

.ml-lesson-section {
  width: var(--reading);
  margin: 0 auto;
  padding: clamp(78px, 10vw, 126px) 0;
  border-top: 1px solid var(--line);
}

.ml-lesson-section > p {
  margin: 22px 0 0;
}

.ml-concept-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 38px;
}

.ml-panel {
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--ml-panel);
}

.ml-panel p {
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.7;
}

.ml-panel code,
.ml-inline-math {
  font-family: var(--ml-math);
  font-size: 1.05em;
}

.ml-statement-list {
  display: grid;
  gap: 16px;
  margin-top: 34px;
}

.ml-statement {
  display: grid;
  grid-template-columns: minmax(220px, 0.65fr) minmax(400px, 1.35fr);
  gap: 22px;
  align-items: center;
  padding: 22px;
  border: 1px solid var(--line);
  background: var(--ml-panel);
}

.ml-statement-formula {
  overflow-x: auto;
  font: 400 28px/1.3 var(--ml-math);
  white-space: nowrap;
}

.ml-statement-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.ml-statement-result {
  grid-column: 2;
  min-height: 24px;
  margin: 0;
  color: var(--muted);
  line-height: 1.55;
}

.ml-prompt {
  margin-top: 38px;
  padding: 24px 0 0 24px;
  border-top: 1px solid var(--line);
  border-left: 3px solid var(--ml-gold);
}

.ml-prompt strong {
  display: block;
  font-family: var(--ml-serif);
  font-size: 24px;
}

.ml-prompt p {
  margin: 10px 0 0;
  color: var(--muted);
  font-family: var(--ml-serif);
  font-size: 18px;
  line-height: 1.7;
}

.ml-geometry-board,
.ml-analysis-board {
  display: grid;
  gap: 18px;
}

.ml-geometry-svg,
.ml-analysis-svg {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  background:
    linear-gradient(color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    var(--surface-strong);
  background-size: 32px 32px;
}

.ml-geometry-svg polygon {
  fill: color-mix(in srgb, var(--accent) 14%, transparent);
  stroke: var(--text);
  stroke-width: 3;
}

.ml-geometry-svg circle {
  fill: var(--ml-cinnabar);
  stroke: var(--text);
  stroke-width: 2;
  cursor: grab;
}

.ml-geometry-svg circle:focus-visible {
  outline: none;
  stroke: var(--gold);
  stroke-width: 6;
}

.ml-geometry-svg text,
.ml-analysis-svg text {
  fill: var(--muted);
  font: 15px var(--ml-sans);
}

.ml-measurements {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.ml-measurements div {
  padding: 12px;
  border-left: 2px solid var(--line-strong);
}

.ml-measurements span {
  display: block;
  color: var(--muted);
  font-size: 12px;
}

.ml-measurements strong {
  display: block;
  margin-top: 6px;
  font: 400 22px var(--ml-math);
}

.ml-analysis-svg .ml-axis {
  stroke: var(--line-strong);
  stroke-width: 2;
}

.ml-analysis-svg .ml-curve {
  fill: none;
  stroke: var(--ml-cinnabar);
  stroke-width: 5;
}

.ml-analysis-svg .ml-average-line {
  fill: none;
  stroke: var(--gold);
  stroke-dasharray: 9 8;
  stroke-width: 3;
}

.ml-analysis-svg .ml-marker {
  fill: var(--text);
  stroke: var(--ml-cinnabar);
  stroke-width: 4;
}

.ml-range-wrap {
  display: grid;
  gap: 9px;
}

.ml-range-wrap label {
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

.ml-range-wrap input[type="range"] {
  width: 100%;
  accent-color: var(--ml-cinnabar);
}

.ml-notebook {
  display: grid;
  grid-template-columns: 0.72fr 1.28fr;
  gap: clamp(30px, 7vw, 86px);
  align-items: start;
}

.ml-notebook h2 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(36px, 4vw, 56px);
  line-height: 1.12;
}

.ml-notebook-prompts {
  counter-reset: prompt;
  display: grid;
  gap: 18px;
}

.ml-notebook-prompts article {
  position: relative;
  padding: 4px 0 20px 58px;
  border-bottom: 1px solid var(--line);
  counter-increment: prompt;
}

.ml-notebook-prompts article::before {
  position: absolute;
  top: 0;
  left: 0;
  color: var(--ml-gold);
  content: counter(prompt, decimal-leading-zero);
  font: 700 12px var(--mono);
}

.ml-notebook-prompts strong {
  font-family: var(--ml-serif);
  font-size: 22px;
}

.ml-notebook-prompts p {
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.65;
}

.ml-next {
  display: grid;
  grid-template-columns: 1.2fr auto;
  gap: 30px;
  align-items: end;
  width: var(--page);
  margin: 0 auto;
  padding: clamp(62px, 9vw, 110px) 0;
  border-top: 1px solid var(--line);
}

.ml-next h2 {
  max-width: 12em;
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(34px, 4.3vw, 58px);
  line-height: 1.12;
}

.ml-next p {
  max-width: 36em;
  margin: 16px 0 0;
  color: var(--muted);
  line-height: 1.7;
}

.ml-share-dialog {
  width: min(520px, calc(100vw - 32px));
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: var(--ml-radius);
  background: var(--surface);
  color: var(--text);
  box-shadow: 0 30px 110px rgba(0, 0, 0, 0.45);
}

.ml-share-dialog::backdrop {
  background: rgba(7, 8, 9, 0.72);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}

.ml-share-dialog-inner {
  padding: 30px;
}

.ml-share-dialog h2 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: 30px;
}

.ml-share-dialog p {
  margin: 14px 0 0;
  color: var(--muted);
  line-height: 1.65;
}

.ml-share-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 24px;
}

.ml-share-status {
  min-height: 22px;
  font-size: 13px;
}

.ml-footer {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 24px;
  align-items: center;
  width: var(--page);
  margin: 0 auto;
  padding: 48px 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}

.ml-footer a:hover,
.ml-footer a:focus-visible {
  color: var(--ml-cinnabar);
}

.ml-noscript {
  width: var(--reading);
  margin: 30px auto;
  padding: 18px;
  border-left: 3px solid var(--ml-cinnabar);
  background: var(--surface);
}

@media (max-width: 1040px) {
  .ml-hub-hero,
  .ml-lesson-hero {
    grid-template-columns: 1fr;
    min-height: 0;
    padding-top: 132px;
  }

  .ml-hero-copy h1,
  .ml-lesson-hero .ml-hero-copy h1 {
    max-width: 12em;
  }

  .ml-lesson-stage {
    min-height: 0;
  }

  .ml-method {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 760px) {
  .math-learning-page .menu-toggle[aria-expanded="true"] ~ .theme-toggle {
    display: none;
  }

  .ml-fixed-tools {
    top: 72px;
    left: 12px;
    right: 12px;
  }

  .ml-tool {
    min-height: 40px;
    padding: 8px 11px;
    font-size: 12px;
  }

  .ml-hub-hero,
  .ml-lesson-hero {
    gap: 36px;
    padding: 126px 0 64px;
  }

  .ml-hero-copy h1,
  .ml-lesson-hero .ml-hero-copy h1 {
    font-size: clamp(44px, 14vw, 62px);
  }

  .ml-hero-copy > p:not(.ml-kicker) {
    font-size: 18px;
  }

  .ml-principles,
  .ml-course-grid,
  .ml-path-map,
  .ml-notebook,
  .ml-next {
    grid-template-columns: 1fr;
  }

  .ml-course--algebra {
    grid-row: auto;
    min-height: 440px;
  }

  .ml-method,
  .ml-path-list,
  .ml-concept-grid {
    grid-template-columns: 1fr;
  }

  .ml-method article {
    min-height: 0;
  }

  .ml-stage-header {
    display: block;
  }

  .ml-stage-label {
    display: inline-block;
    margin-top: 14px;
  }

  .ml-equation {
    font-size: clamp(36px, 12vw, 54px);
  }

  .ml-statement {
    grid-template-columns: 1fr;
  }

  .ml-statement-result {
    grid-column: 1;
  }

  .ml-measurements {
    grid-template-columns: 1fr 1fr;
  }

  .ml-next {
    align-items: start;
  }

  .ml-footer {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .ml-balance-beam,
  .ml-tool,
  .ml-button,
  .ml-choice,
  .ml-preset,
  .ml-course-link {
    transition: none;
  }
}

/* Linked inquiry labs: prediction, manipulation, and synchronized representations. */
.ml-prediction-gate {
  display: grid;
  gap: 18px;
  padding: 20px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--ml-gold);
  background: color-mix(in srgb, var(--ml-gold) 7%, var(--surface));
}

.ml-prediction-gate > div:first-child strong,
.ml-invariant-control > div:first-child strong {
  display: block;
  font: 600 19px/1.3 var(--ml-serif);
}

.ml-prediction-gate p,
.ml-invariant-control p {
  margin: 5px 0 0;
  color: var(--muted);
  line-height: 1.55;
}

.ml-prediction-control {
  display: grid;
  grid-template-columns: minmax(190px, 1fr) auto;
  gap: 12px 18px;
  align-items: end;
}

.ml-prediction-control label {
  grid-column: 1 / -1;
  color: var(--text);
  font-weight: 700;
}

.ml-prediction-control input {
  width: 100%;
  accent-color: var(--ml-cinnabar);
}

.ml-prediction-gate.is-committed {
  border-left-color: var(--ml-cinnabar);
  background: color-mix(in srgb, var(--ml-cinnabar) 6%, var(--surface));
}

.ml-algebra-linked,
.ml-analysis-experiment {
  display: grid;
  gap: 20px;
  margin-top: 20px;
}

.ml-algebra-linked[hidden],
.ml-analysis-experiment[hidden],
.ml-invariant-control[hidden] {
  display: none;
}

.ml-equation--relation {
  display: grid;
  grid-template-columns: 1fr 54px 1fr;
  align-items: center;
  margin: 0;
  padding: 18px 20px;
  background: var(--surface-strong);
}

.ml-equation--relation span:first-child { text-align: right; }
.ml-equation--relation span:last-child { text-align: left; }
.ml-equation--relation b {
  color: var(--ml-cinnabar);
  font: 700 34px/1 var(--ml-math);
  text-align: center;
  transition: color 180ms ease, transform 180ms var(--ease);
}

.ml-equation--relation b[data-relation="equal"] {
  color: var(--ml-gold);
  transform: scale(1.16);
}

.ml-substitution {
  min-height: 1.5em;
  margin: -10px 0 0;
  color: var(--muted);
  font-family: var(--ml-math);
  text-align: center;
}

.ml-linked-bars {
  display: grid;
  gap: 14px;
  padding: 18px;
  border: 1px solid var(--line);
  background: var(--surface);
}

.ml-linked-bar {
  display: grid;
  grid-template-columns: 76px minmax(0, 1fr) 32px;
  gap: 12px;
  align-items: center;
}

.ml-linked-bar > span {
  color: var(--muted);
  font: 700 11px/1.2 var(--mono);
  text-transform: uppercase;
}

.ml-linked-bar > i {
  display: block;
  overflow: hidden;
  height: 18px;
  border: 1px solid var(--line-strong);
  background: color-mix(in srgb, var(--text) 5%, transparent);
}

.ml-linked-bar > i > b {
  display: block;
  width: 100%;
  height: 100%;
  background: var(--ml-cinnabar);
  transform: scaleX(.45);
  transform-origin: left center;
  transition: transform 240ms var(--ease);
}

.ml-linked-bar--fixed > i > b { background: var(--ml-gold); }
.ml-linked-bar > strong { font: 700 16px/1 var(--mono); }

.ml-range-wrap--focus {
  padding: 14px 16px;
  border: 1px solid var(--line-strong);
  background: color-mix(in srgb, var(--ml-cinnabar) 5%, var(--surface));
}

.ml-solution-line {
  display: grid;
  grid-template-columns: repeat(9, minmax(0, 1fr));
  gap: 5px;
}

.ml-solution-line button {
  display: grid;
  min-width: 0;
  min-height: 52px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
}

.ml-solution-line button span { font: 700 14px/1 var(--mono); }
.ml-solution-line button b { color: var(--muted); font: 700 15px/1 var(--ml-math); }
.ml-solution-line button:hover,
.ml-solution-line button:focus-visible,
.ml-solution-line button.is-current { border-color: var(--ml-cinnabar); }
.ml-solution-line button.is-current { background: color-mix(in srgb, var(--ml-cinnabar) 12%, var(--surface)); }
.ml-solution-line button.is-solution b { color: var(--ml-gold); }

.ml-invariant-control {
  display: grid;
  grid-template-columns: minmax(200px, .8fr) minmax(260px, 1.2fr);
  gap: 18px;
  align-items: center;
  padding: 18px;
  border: 1px solid color-mix(in srgb, var(--ml-gold) 60%, var(--line));
  background: color-mix(in srgb, var(--ml-gold) 8%, var(--surface));
}

.ml-dependency-key {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 16px;
}

.ml-dependency-key > span {
  display: grid;
  grid-template-columns: 18px 1fr;
  gap: 4px 8px;
  align-items: center;
  padding: 10px 12px;
  border: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

.ml-dependency-key > span b {
  color: var(--text);
  font-size: 12px;
}

.ml-dependency-key i {
  grid-row: 1 / 3;
  width: 14px;
  height: 14px;
}

.ml-free-point-key {
  border: 2px solid var(--text);
  border-radius: 50%;
  background: var(--ml-cinnabar);
}

.ml-dependent-key {
  border: 2px solid var(--ml-gold);
  border-radius: 50% 50% 0 50%;
}

.ml-claim-box small {
  display: block;
  margin-top: 10px;
  color: var(--muted);
  line-height: 1.5;
}

.ml-mode-bank {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.ml-road-checkpoints {
  position: absolute;
  inset: 0;
  z-index: 1;
}

.ml-road-checkpoints > span {
  position: absolute;
  top: 0;
  transform: translateX(-50%);
}

.ml-road-checkpoints > span:first-child { transform: none; }
.ml-road-checkpoints > span:last-child { transform: translateX(-100%); }
.ml-road-checkpoints i {
  display: block;
  width: 8px;
  height: 8px;
  margin-top: -1px;
  border: 2px solid var(--muted);
  border-radius: 50%;
  background: var(--surface-strong);
  transition: background 160ms ease, border-color 160ms ease, transform 160ms var(--ease);
}

.ml-road-checkpoints b {
  top: -26px;
  left: 50%;
  transform: translateX(-50%);
  white-space: nowrap;
}

.ml-road-checkpoints > span:first-child b { left: 0; transform: none; }
.ml-road-checkpoints > span:last-child b { right: 0; left: auto; transform: none; }
.ml-road-checkpoints > span.is-passed i { border-color: var(--ml-cinnabar); background: var(--ml-cinnabar); }
.ml-road-checkpoints > span.is-current i { transform: scale(1.65); }
.ml-road-checkpoints > span.is-stacked b { top: -42px; }
.ml-traveller { z-index: 3; }

.ml-motion-linked-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(170px, .65fr);
  gap: 16px;
  align-items: stretch;
}

.ml-time-cursor {
  stroke: color-mix(in srgb, var(--ml-gold) 68%, transparent);
  stroke-width: 2;
  stroke-dasharray: 4 5;
}

.ml-graph-checkpoint {
  fill: var(--surface-strong);
  stroke: var(--muted);
  stroke-width: 2;
  transition: fill 160ms ease, stroke 160ms ease, r 160ms var(--ease);
}

.ml-graph-checkpoint.is-passed { fill: var(--ml-cinnabar); stroke: var(--ml-cinnabar); }
.ml-graph-checkpoint.is-current { fill: var(--ml-gold); stroke: var(--ml-gold); r: 7px; }

.ml-motion-table-wrap {
  overflow: auto;
  border: 1px solid var(--line);
  background: var(--surface);
}

.ml-motion-table {
  width: 100%;
  border-collapse: collapse;
  font-variant-numeric: tabular-nums;
}

.ml-motion-table caption {
  padding: 12px 10px;
  border-bottom: 1px solid var(--line);
  color: var(--muted);
  font: 700 11px/1.3 var(--mono);
  text-align: left;
}

.ml-motion-table th,
.ml-motion-table td {
  padding: 9px 8px;
  border-bottom: 1px solid var(--line);
  font: 700 11px/1.2 var(--mono);
  text-align: right;
  white-space: nowrap;
}

.ml-motion-table thead th { color: var(--muted); }
.ml-motion-table tbody th { color: var(--text); }
.ml-motion-table tbody tr.is-current { background: color-mix(in srgb, var(--ml-cinnabar) 12%, var(--surface)); }
.ml-motion-table tbody tr:last-child th,
.ml-motion-table tbody tr:last-child td { border-bottom: 0; }

@media (max-width: 900px) {
  .ml-motion-linked-grid { grid-template-columns: 1fr; }
  .ml-motion-table-wrap { max-height: 250px; }
}

@media (max-width: 760px) {
  .ml-prediction-control,
  .ml-invariant-control,
  .ml-dependency-key,
  .ml-mode-bank {
    grid-template-columns: 1fr;
  }

  .ml-prediction-control .ml-button { width: 100%; }
  .ml-equation--relation { grid-template-columns: 1fr 42px 1fr; padding: 14px 10px; }
  .ml-linked-bar { grid-template-columns: 64px minmax(0, 1fr) 28px; gap: 8px; }
  .ml-solution-line { gap: 3px; }
  .ml-solution-line button { min-height: 46px; }
  .ml-road-checkpoints b { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .ml-equation--relation b,
  .ml-linked-bar > i > b,
  .ml-road-checkpoints i,
  .ml-graph-checkpoint {
    transition: none !important;
  }
}

/* Equality lab: one visible operation at a time. */
.ml-balance-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  justify-content: center;
  margin: 18px 0 4px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.ml-balance-legend span {
  display: inline-flex;
  gap: 8px;
  align-items: center;
}

.ml-balance-legend i {
  flex: 0 0 auto;
  width: 24px;
  height: 24px;
  font-style: normal;
}

.ml-balance-legend .ml-variable-token {
  width: 34px;
}

.ml-balance-guide {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: center;
  min-height: 60px;
  padding: 14px 18px;
  border-left: 3px solid var(--ml-cinnabar);
  background: color-mix(in srgb, var(--surface-strong) 74%, transparent);
}

.ml-balance-guide span {
  color: var(--muted);
  line-height: 1.45;
}

.ml-balance-guide strong {
  color: var(--text);
  font: 700 12px var(--mono);
  text-align: right;
}

.ml-balance-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.ml-balance-actions .ml-button {
  white-space: nowrap;
}

.ml-balance-actions .ml-button[hidden] {
  display: none !important;
}

.ml-balance-actions .ml-button[disabled] {
  cursor: not-allowed;
  opacity: 0.46;
}

.ml-balance-v2 .ml-unit-token.is-leaving {
  animation: ml-matching-pair-leave 500ms var(--ease) both;
}

@keyframes ml-matching-pair-leave {
  0% { opacity: 1; transform: translateY(0) scale(1); }
  55% { opacity: 1; transform: translateY(-26px) scale(1.08); }
  100% { opacity: 0; transform: translateY(-48px) scale(0.72); }
}

.ml-balance-v2.is-solved .ml-variable-token {
  background: color-mix(in srgb, var(--ml-cinnabar) 52%, var(--surface));
  transform: scale(1.14);
  transition: transform 360ms var(--ease), background 360ms ease;
}

.ml-balance-v2.is-solved .ml-balance-v2-beam {
  box-shadow: 0 3px 0 color-mix(in srgb, var(--ml-cinnabar) 35%, transparent);
}

.ml-balance-v2.is-broken .ml-balance-v2-pan--left {
  color: var(--ml-cinnabar);
}

@media (max-width: 760px) {
  .ml-balance-legend {
    justify-content: flex-start;
  }

  .ml-balance-guide {
    grid-template-columns: 1fr;
    gap: 5px;
  }

  .ml-balance-guide strong {
    text-align: left;
  }

  .ml-balance-actions {
    justify-content: stretch;
  }

  .ml-balance-actions .ml-button {
    flex: 1 1 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  .ml-balance-v2 .ml-unit-token.is-leaving {
    animation: none !important;
    opacity: 0;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .ml-tool {
    background: var(--bg);
    -webkit-backdrop-filter: none;
    backdrop-filter: none;
  }
}

/* Interactive learning laboratory, revision 2 */

.ml-enter {
  opacity: 0;
  transform: translateY(24px);
  animation: ml-enter 720ms var(--ease) forwards;
}

.ml-enter--late {
  animation-delay: 140ms;
}

.ml-reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 650ms var(--ease), transform 650ms var(--ease);
}

.ml-reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@keyframes ml-enter {
  to { opacity: 1; transform: translateY(0); }
}

.ml-lesson-hero--play {
  grid-template-columns: minmax(280px, 0.58fr) minmax(620px, 1.42fr);
  gap: clamp(38px, 5vw, 76px);
  align-items: start;
  padding-top: clamp(84px, 9vh, 104px);
  padding-bottom: clamp(46px, 6vh, 66px);
}

.ml-lesson-hero--play .ml-hero-copy h1 {
  font-size: clamp(44px, 4.6vw, 70px);
}

.ml-lesson-hero--play .ml-hero-copy > p:not(.ml-kicker) {
  max-width: 20em;
}

.ml-lesson-hero--play .ml-lesson-stage {
  min-height: 0;
}

.ml-connection-layout {
  display: grid;
  grid-template-columns: minmax(250px, 0.5fr) minmax(620px, 1.5fr);
  gap: clamp(36px, 7vw, 100px);
  align-items: center;
}

.ml-connection-lab,
.ml-scanner-stage,
.ml-formula-deck,
.ml-angle-assembly,
.ml-evidence-stage,
.ml-story-lab,
.ml-zoom-stage {
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--ml-panel);
  box-shadow: 0 24px 80px var(--shadow);
}

.ml-connection-lab {
  padding: clamp(22px, 3.4vw, 38px);
}

.ml-connection-equation {
  margin-bottom: 18px;
  font: 400 clamp(34px, 4vw, 58px)/1 var(--ml-math);
  text-align: center;
}

.ml-connection-svg,
.ml-zoom-svg {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  background:
    linear-gradient(color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    var(--surface-strong);
  background-size: 32px 32px;
}

.ml-connection-svg .ml-axis,
.ml-zoom-svg .ml-axis {
  stroke: var(--line-strong);
  stroke-width: 2;
}

.ml-connection-svg text {
  fill: var(--muted);
  font: 15px var(--ml-sans);
}

.ml-connection-curve,
.ml-curve-guide {
  fill: none;
  stroke: color-mix(in srgb, var(--text) 34%, transparent);
  stroke-width: 3;
}

.ml-connection-tangent,
.ml-secant {
  stroke: var(--ml-gold);
  stroke-dasharray: 10 8;
  stroke-width: 3;
  transition: transform 280ms var(--ease), opacity 280ms ease;
}

.ml-connection-point {
  fill: var(--ml-cinnabar);
  stroke: var(--text);
  stroke-width: 3;
  transition: cx 180ms var(--ease), cy 180ms var(--ease);
}

.ml-lens-controls,
.ml-loop-controls,
.ml-choice-bank,
.ml-run-row,
.ml-play-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.ml-lens-controls {
  margin-top: 18px;
}

.ml-connection-readouts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 16px;
}

.ml-connection-readouts div {
  min-height: 88px;
  padding: 14px;
  border: 1px solid var(--line);
  opacity: 0.52;
  transform: translateY(5px);
  transition: opacity 220ms ease, transform 220ms var(--ease), border-color 220ms ease;
}

.ml-connection-readouts div.is-active {
  border-color: var(--ml-cinnabar);
  opacity: 1;
  transform: translateY(0);
}

.ml-connection-readouts span,
.ml-rate-readout span {
  display: block;
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.ml-connection-readouts strong {
  display: block;
  margin-top: 9px;
  font: 400 17px/1.35 var(--ml-math);
}

.ml-symbol--balance {
  display: grid;
  grid-template-columns: auto 1fr auto 1fr auto;
  gap: 10px;
  align-items: end;
  width: min(100%, 520px);
  font-size: clamp(45px, 6vw, 82px);
}

.ml-symbol--balance i {
  height: 2px;
  margin-bottom: 14px;
  background: var(--line-strong);
  transform: scaleX(0.25);
  transform-origin: left;
  transition: transform 420ms var(--ease);
}

.ml-course--algebra:hover .ml-symbol--balance i,
.ml-course--algebra:focus-within .ml-symbol--balance i {
  transform: scaleX(1);
}

.ml-symbol--triangle {
  transform-origin: 50% 65%;
  transition: transform 420ms var(--ease);
}

.ml-course--geometry:hover .ml-symbol--triangle,
.ml-course--geometry:focus-within .ml-symbol--triangle {
  transform: rotate(12deg) scale(1.06);
}

.ml-symbol--curve {
  transition: transform 420ms var(--ease);
}

.ml-course--analysis:hover .ml-symbol--curve,
.ml-course--analysis:focus-within .ml-symbol--curve {
  transform: translateY(-10px) skewY(-8deg);
}

.ml-loop-lab {
  display: grid;
  grid-template-columns: minmax(230px, 0.55fr) minmax(360px, 1.05fr);
  gap: clamp(30px, 7vw, 94px);
  align-items: center;
}

.ml-loop-lab .ml-loop-controls {
  grid-column: 2;
  justify-content: center;
}

.ml-loop-stage {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 360px;
  border: 1px solid var(--line);
  background: var(--ml-panel);
  overflow: hidden;
  text-align: center;
}

.ml-loop-stage strong {
  font-family: var(--ml-serif);
  font-size: clamp(42px, 6vw, 76px);
  font-weight: 600;
  transition: opacity 180ms ease, transform 180ms var(--ease);
}

.ml-loop-stage p {
  position: absolute;
  bottom: 34px;
  max-width: 24em;
  margin: 0;
  color: var(--muted);
}

.ml-loop-stage.is-changing strong,
.ml-loop-stage.is-changing p {
  opacity: 0;
  transform: translateY(10px);
}

.ml-loop-orbit {
  position: absolute;
  inset: 50% auto auto 50%;
  width: 250px;
  height: 250px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

.ml-loop-orbit span {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 15px;
  height: 15px;
  margin: -7px;
  border: 2px solid var(--text);
  border-radius: 50%;
  background: var(--ml-cinnabar);
  transform: rotate(var(--orbit-angle)) translateX(125px);
  transition: transform 520ms var(--ease);
}

.ml-loop-orbit span:nth-child(2) { --orbit-angle: 120deg; }
.ml-loop-orbit span:nth-child(3) { --orbit-angle: 240deg; }

.ml-loop-stage[data-loop-index="1"] .ml-loop-orbit span { transform: rotate(calc(var(--orbit-angle, 0deg) + 90deg)) translateX(125px); }
.ml-loop-stage[data-loop-index="2"] .ml-loop-orbit span { transform: rotate(calc(var(--orbit-angle, 0deg) + 180deg)) translateX(125px); }
.ml-loop-stage[data-loop-index="3"] .ml-loop-orbit span { transform: rotate(calc(var(--orbit-angle, 0deg) + 270deg)) translateX(125px); }

.ml-curiosity-band {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 26px;
  align-items: baseline;
  width: var(--page);
  margin: 0 auto;
  padding: 70px 0;
  border-top: 1px solid var(--line);
}

.ml-curiosity-band strong {
  color: var(--ml-gold);
  font: 700 12px var(--mono);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.ml-curiosity-band p {
  margin: 0;
  font: 400 clamp(26px, 3.4vw, 46px)/1.25 var(--ml-serif);
}

.ml-lab-section {
  padding: clamp(76px, 10vw, 132px) 0;
  border-top: 1px solid var(--line);
}

.ml-lab-split,
.ml-deck-layout,
.ml-evidence-lab {
  display: grid;
  grid-template-columns: minmax(230px, 0.55fr) minmax(520px, 1.45fr);
  gap: clamp(34px, 7vw, 96px);
  align-items: center;
}

.ml-lab-copy h2,
.ml-rule-band h2,
.ml-question-pair h2 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(36px, 4.5vw, 62px);
  font-weight: 600;
  letter-spacing: -0.045em;
  line-height: 1.08;
}

.ml-lab-copy p {
  max-width: 27em;
  margin: 18px 0 0;
  color: var(--muted);
  font-family: var(--ml-serif);
  font-size: 18px;
  line-height: 1.65;
}

.ml-balance-v2 {
  position: relative;
  height: 210px;
  margin: 8px 0 18px;
}

.ml-balance-v2-beam {
  position: absolute;
  top: 104px;
  left: 10%;
  width: 80%;
  height: 4px;
  background: var(--text);
  transform: rotate(var(--balance-tilt, 0deg));
  transform-origin: center;
  transition: transform 620ms cubic-bezier(0.22, 1.3, 0.36, 1);
}

.ml-balance-v2-pan {
  position: absolute;
  bottom: 18px;
  display: grid;
  gap: 8px;
  justify-items: center;
  width: 41%;
  min-height: 84px;
  padding: 8px;
  border-bottom: 3px solid var(--ml-cinnabar);
}

.ml-balance-v2-pan::after {
  position: absolute;
  bottom: -20px;
  left: 50%;
  width: 1px;
  height: 20px;
  background: var(--line-strong);
  content: "";
}

.ml-balance-v2-pan--left { left: -7%; }
.ml-balance-v2-pan--right { right: -7%; }

.ml-balance-v2-pan > span {
  color: var(--muted);
  font: 700 12px var(--mono);
}

.ml-balance-v2-stand {
  position: absolute;
  top: 105px;
  left: calc(50% - 3px);
  width: 6px;
  height: 88px;
  background: var(--ml-gold);
}

.ml-balance-v2-stand::after {
  position: absolute;
  bottom: 0;
  left: -48px;
  width: 102px;
  height: 4px;
  background: var(--ml-gold);
  content: "";
}

.ml-token-row {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  justify-content: center;
  align-content: end;
  min-height: 48px;
}

.ml-unit-token,
.ml-variable-token {
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  border: 1px solid var(--text);
  background: var(--surface-strong);
  color: var(--text);
  font: 700 12px var(--ml-math);
}

.ml-unit-token { border-radius: 50%; }

.ml-variable-token {
  width: 39px;
  border-color: var(--ml-cinnabar);
  background: color-mix(in srgb, var(--ml-cinnabar) 28%, var(--surface));
  font-size: 16px;
}

.ml-balance-v2.is-running .ml-unit-token,
.ml-balance-v2.is-running .ml-variable-token {
  animation: ml-token-hop 520ms var(--ease) both;
}

.ml-balance-v2.is-running .ml-token-row > :nth-child(2n) { animation-delay: 55ms; }
.ml-balance-v2.is-running .ml-token-row > :nth-child(3n) { animation-delay: 105ms; }

@keyframes ml-token-hop {
  0% { transform: translateY(0); }
  45% { transform: translateY(-18px) rotate(5deg); }
  100% { transform: translateY(0); }
}

.ml-balance-sparks,
.ml-solution-burst {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.ml-balance-sparks i,
.ml-solution-burst i {
  position: absolute;
  top: 48%;
  left: 50%;
  width: 7px;
  height: 7px;
  background: var(--ml-gold);
  opacity: 0;
}

.ml-balance-v2.is-balanced .ml-balance-sparks i,
.ml-tower-field.is-solved .ml-solution-burst i {
  animation: ml-burst 650ms var(--ease) both;
}

.ml-balance-sparks i:nth-child(2), .ml-solution-burst i:nth-child(2) { --burst-x: 70px; --burst-y: -45px; animation-delay: 60ms; }
.ml-balance-sparks i:nth-child(3), .ml-solution-burst i:nth-child(3) { --burst-x: -60px; --burst-y: -55px; animation-delay: 100ms; }
.ml-balance-sparks i:nth-child(4), .ml-solution-burst i:nth-child(4) { --burst-x: 42px; --burst-y: 58px; animation-delay: 140ms; }
.ml-solution-burst i:nth-child(5) { --burst-x: -54px; --burst-y: 48px; animation-delay: 180ms; }

@keyframes ml-burst {
  0% { opacity: 0; transform: translate(0, 0) scale(0.3) rotate(0); }
  35% { opacity: 1; }
  100% { opacity: 0; transform: translate(var(--burst-x, -70px), var(--burst-y, -40px)) scale(1.2) rotate(90deg); }
}

.ml-choice-bank {
  justify-content: center;
}

.ml-predict-row {
  display: grid;
  grid-template-columns: auto 1fr 1fr;
  gap: 9px;
  align-items: center;
  margin-top: 14px;
}

.ml-predict-row > span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.ml-run-row,
.ml-play-row {
  justify-content: center;
  margin-top: 14px;
}

.ml-scanner-stage,
.ml-formula-deck,
.ml-angle-assembly,
.ml-zoom-stage {
  padding: clamp(24px, 4vw, 42px);
}

.ml-scanner-equation {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 20px;
  align-items: center;
  font: 400 clamp(32px, 4vw, 54px)/1 var(--ml-math);
  text-align: center;
}

.ml-scanner-equation b {
  color: var(--ml-cinnabar);
  font-weight: 400;
}

.ml-tower-field {
  position: relative;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 28px;
  align-items: end;
  height: 280px;
  margin: 24px 0;
}

.ml-number-tower {
  position: relative;
  display: grid;
  place-items: end center;
  height: 250px;
  border-bottom: 3px solid var(--line-strong);
}

.ml-number-tower i {
  position: absolute;
  bottom: 3px;
  width: min(60%, 120px);
  height: 220px;
  background: color-mix(in srgb, var(--ml-cinnabar) 38%, var(--surface));
  transform: scaleY(0.28);
  transform-origin: bottom;
  transition: transform 380ms var(--ease);
}

.ml-number-tower:nth-of-type(3) i {
  background: color-mix(in srgb, var(--ml-gold) 42%, var(--surface));
  transform: scaleY(0.64);
}

.ml-number-tower strong,
.ml-number-tower span {
  position: relative;
  z-index: 1;
}

.ml-number-tower strong {
  align-self: start;
  margin-top: 16px;
  font: 400 32px var(--ml-math);
}

.ml-number-tower span {
  margin-bottom: -26px;
  color: var(--muted);
  font-size: 12px;
}

.ml-equality-pulse {
  align-self: center;
  color: var(--ml-cinnabar);
  font: 400 42px var(--ml-math);
  transition: transform 320ms var(--ease), color 320ms ease;
}

.ml-tower-field.is-solved .ml-equality-pulse {
  color: var(--ml-gold);
  transform: scale(1.35);
}

.ml-deck-count {
  color: var(--muted);
  font: 700 11px var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.ml-deck-formula {
  min-height: 130px;
  padding: 30px 0;
  font: 400 clamp(40px, 6vw, 74px)/1.15 var(--ml-math);
  text-align: center;
  transition: opacity 180ms ease, transform 180ms var(--ease);
}

.ml-formula-deck.is-changing .ml-deck-formula {
  opacity: 0;
  transform: translateX(28px) rotate(1deg);
}

.ml-formula-deck .ml-button[disabled],
.ml-story-result .ml-button[disabled] {
  cursor: not-allowed;
  opacity: 0.45;
}

.ml-rule-band {
  width: var(--page);
  margin: 0 auto;
  padding: clamp(78px, 10vw, 130px) 0;
  border-top: 1px solid var(--line);
}

.ml-rule-formula {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 24px;
  align-items: center;
  margin-top: 42px;
  font: 400 clamp(30px, 4vw, 56px)/1.2 var(--ml-math);
}

.ml-rule-formula span {
  padding: 26px;
  border: 1px solid var(--line);
  background: var(--ml-panel);
  text-align: center;
}

.ml-rule-formula b {
  color: var(--ml-gold);
  font: 700 12px var(--mono);
  text-transform: uppercase;
}

.ml-question-pair {
  display: grid;
  grid-template-columns: 0.8fr 1fr 1fr;
  gap: clamp(22px, 5vw, 64px);
  align-items: start;
  width: var(--page);
  margin: 0 auto;
  padding: clamp(72px, 9vw, 112px) 0;
  border-top: 1px solid var(--line);
}

.ml-question-pair h2 {
  font-size: clamp(32px, 3.6vw, 48px);
}

.ml-question-pair p {
  margin: 0;
  padding: 22px 0;
  border-top: 2px solid var(--ml-gold);
  color: var(--muted);
  font-family: var(--ml-serif);
  font-size: 20px;
  line-height: 1.55;
}

.ml-angle-arc {
  fill: none;
  stroke-width: 6;
  stroke-linecap: round;
  pointer-events: none;
  transition: d 180ms var(--ease);
}

.ml-angle-arc--a { stroke: var(--ml-cinnabar); }
.ml-angle-arc--b { stroke: var(--ml-gold); }
.ml-angle-arc--c { stroke: color-mix(in srgb, var(--text) 65%, transparent); }

.ml-angle-dashboard {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}

.ml-angle-dashboard div {
  padding: 12px 14px;
  border-left: 3px solid var(--line-strong);
}

.ml-angle-dashboard div:nth-child(1) { border-color: var(--ml-cinnabar); }
.ml-angle-dashboard div:nth-child(2) { border-color: var(--ml-gold); }

.ml-angle-dashboard span {
  display: block;
  color: var(--muted);
  font-size: 11px;
  text-transform: uppercase;
}

.ml-angle-dashboard strong {
  display: block;
  margin-top: 4px;
  font: 400 22px var(--ml-math);
}

.ml-angle-sum strong {
  color: var(--ml-cinnabar);
}

.ml-claim-box {
  display: grid;
  gap: 9px;
}

.ml-claim-box > span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
  text-align: center;
}

.ml-angle-assembly {
  position: relative;
  min-height: 520px;
  overflow: hidden;
}

.ml-proof-triangle {
  position: absolute;
  inset: 54px 15% 130px;
  opacity: 0.6;
  transition: opacity 360ms ease, transform 520ms var(--ease);
}

.ml-proof-edge {
  position: absolute;
  height: 2px;
  background: var(--line-strong);
  transform-origin: left center;
}

.ml-proof-edge--left { top: 22px; left: 50%; width: 57%; transform: rotate(134deg); }
.ml-proof-edge--right { top: 22px; left: 50%; width: 57%; transform: rotate(46deg); }
.ml-proof-edge--base { bottom: 16px; left: 15%; width: 70%; }

.ml-angle-piece {
  position: absolute;
  z-index: 2;
  width: 140px;
  height: 140px;
  transform: translate(0, 0);
  transform-origin: center;
  transition: transform 820ms cubic-bezier(0.22, 1.2, 0.36, 1);
}

.ml-angle-piece svg {
  display: block;
  width: 100%;
  height: 100%;
  overflow: visible;
}

.ml-angle-piece svg path:first-child {
  fill: color-mix(in srgb, var(--surface-strong) 78%, transparent);
  stroke: var(--line-strong);
  stroke-width: 2;
}

.ml-angle-piece--a svg path:first-child { fill: color-mix(in srgb, var(--ml-cinnabar) 24%, var(--surface-strong)); }
.ml-angle-piece--b svg path:first-child { fill: color-mix(in srgb, var(--ml-gold) 28%, var(--surface-strong)); }
.ml-angle-piece--c svg path:first-child { fill: color-mix(in srgb, var(--text) 12%, var(--surface-strong)); }

.ml-angle-piece .ml-angle-piece-arc {
  fill: none;
  stroke: currentColor;
  stroke-width: 4;
}

.ml-angle-piece-label {
  position: absolute;
  top: 50%;
  left: 73%;
  display: grid;
  gap: 1px;
  justify-items: center;
  transform: translate(-50%, -50%);
  transition: transform 820ms cubic-bezier(0.22, 1.2, 0.36, 1), opacity 220ms ease;
}

.ml-angle-piece-label b {
  color: var(--muted);
  font: 700 10px var(--mono);
}

.ml-angle-piece-label strong { font: 400 17px var(--ml-math); }
.ml-angle-piece--a { bottom: 112px; left: 6%; color: var(--ml-cinnabar); --piece-rotation: -156.8deg; --label-rotation: 156.8deg; }
.ml-angle-piece--b { right: 6%; bottom: 112px; color: var(--ml-gold); --piece-rotation: -23.2deg; --label-rotation: 23.2deg; }
.ml-angle-piece--c { top: 20px; left: calc(50% - 70px); color: var(--text); --piece-rotation: -90deg; --label-rotation: 90deg; }

.ml-angle-assembly.is-assembled .ml-angle-piece {
  transform: translate(var(--piece-x, 0), var(--piece-y, 0)) rotate(var(--piece-rotation));
}

.ml-angle-assembly.is-assembled .ml-angle-piece-label {
  transform: translate(-50%, -50%) rotate(var(--label-rotation));
  opacity: 0;
}

.ml-angle-assembly.is-assembled .ml-proof-triangle {
  opacity: 0.18;
  transform: scale(0.96);
}

.ml-straight-angle {
  position: absolute;
  right: 13%;
  bottom: 132px;
  left: 13%;
  display: flex;
  justify-content: flex-end;
  align-items: end;
  height: 4px;
  background: var(--text);
  opacity: 0;
  transform: scaleX(0.2);
  transition: opacity 260ms ease 420ms, transform 520ms var(--ease) 360ms;
}

.ml-straight-angle strong {
  padding-bottom: 12px;
  text-align: center;
}

.ml-straight-angle strong { color: var(--ml-cinnabar); font: 400 25px var(--ml-math); }

.ml-angle-assembly.is-assembled .ml-straight-angle {
  opacity: 1;
  transform: scaleX(1);
}

.ml-section[id] {
  scroll-margin-top: 150px;
}

.ml-angle-assembly .ml-run-row {
  position: absolute;
  right: 0;
  bottom: 20px;
  left: 0;
}

.ml-angle-assembly .ml-feedback {
  position: absolute;
  right: 0;
  bottom: 72px;
  left: 0;
}

.ml-evidence-lab {
  grid-template-columns: minmax(220px, 0.5fr) minmax(360px, 1fr);
}

.ml-evidence-lab .ml-loop-controls {
  grid-column: 2;
  justify-content: center;
}

.ml-evidence-stage {
  display: grid;
  place-items: center;
  min-height: 330px;
  padding: 28px;
  text-align: center;
}

.ml-evidence-stage strong {
  margin-top: 20px;
  font: 600 clamp(36px, 5vw, 62px)/1 var(--ml-serif);
}

.ml-evidence-stage p {
  margin: 14px 0 0;
  color: var(--muted);
}

.ml-evidence-visual {
  position: relative;
  width: 170px;
  height: 110px;
}

.ml-evidence-visual i {
  position: absolute;
  top: 42px;
  width: 34px;
  height: 34px;
  border: 2px solid var(--text);
  border-radius: 50%;
  background: var(--surface-strong);
  transition: transform 520ms var(--ease), background 320ms ease, border-radius 320ms ease;
}

.ml-evidence-visual i:nth-child(1) { left: 8px; }
.ml-evidence-visual i:nth-child(2) { left: 68px; }
.ml-evidence-visual i:nth-child(3) { right: 8px; }
.ml-evidence-stage[data-evidence-mode="experiment"] .ml-evidence-visual i:nth-child(1) { transform: translateY(-24px); }
.ml-evidence-stage[data-evidence-mode="experiment"] .ml-evidence-visual i:nth-child(3) { transform: translateY(24px); }
.ml-evidence-stage[data-evidence-mode="counterexample"] .ml-evidence-visual i:nth-child(2) { background: var(--ml-cinnabar); transform: scale(1.45); }
.ml-evidence-stage[data-evidence-mode="proof"] .ml-evidence-visual i { border-radius: 2px; background: color-mix(in srgb, var(--ml-gold) 30%, var(--surface)); }

.ml-road-scene {
  padding: 18px 12px 28px;
}

.ml-road-track {
  position: relative;
  height: 6px;
  margin: 38px 18px 0;
  background: var(--line-strong);
}

.ml-road-track::before,
.ml-road-track::after {
  position: absolute;
  top: -8px;
  width: 2px;
  height: 22px;
  background: var(--text);
  content: "";
}

.ml-road-track::before { left: 0; }
.ml-road-track::after { right: 0; }

.ml-road-track b {
  position: absolute;
  top: 18px;
  color: var(--muted);
  font: 700 11px var(--mono);
}

.ml-road-track b:first-of-type { left: 0; }
.ml-road-track b:last-of-type { right: 0; }

.ml-traveller {
  position: absolute;
  top: -17px;
  left: -2px;
  width: 38px;
  height: 38px;
  border: 3px solid var(--text);
  border-radius: 50%;
  background: var(--ml-cinnabar);
  transform: translateX(0);
  transition: transform 100ms linear;
}

.ml-traveller i {
  position: absolute;
  top: 9px;
  left: 9px;
  width: 13px;
  height: 13px;
  border: 2px solid #f8eee3;
  border-radius: 50%;
}

.ml-curve-guide {
  stroke-dasharray: 7 8;
}

.ml-analysis-svg .ml-curve {
  stroke-dasharray: 1;
  stroke-dashoffset: 1;
  transition: stroke-dashoffset 100ms linear;
}

.ml-mini-graphs {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr 1fr;
  gap: 14px;
  margin-top: 34px;
}

.ml-mini-graphs button {
  min-width: 0;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: var(--ml-radius);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: transform 220ms var(--ease), border-color 220ms ease, background 220ms ease;
}

.ml-mini-graphs button:hover,
.ml-mini-graphs button:focus-visible {
  border-color: var(--ml-cinnabar);
  transform: translateY(-5px);
}

.ml-mini-graphs button.is-correct { border-color: var(--ml-gold); background: color-mix(in srgb, var(--ml-gold) 14%, var(--surface)); }
.ml-mini-graphs button.is-wrong { animation: ml-shake 360ms ease; }

@keyframes ml-shake {
  0%, 100% { transform: translateX(0); }
  30% { transform: translateX(-8px); }
  65% { transform: translateX(7px); }
}

.ml-mini-graphs svg {
  display: block;
  width: 100%;
  height: auto;
}

.ml-mini-graphs path {
  fill: none;
  stroke: var(--ml-cinnabar);
  stroke-width: 5;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.ml-mini-graphs span {
  display: block;
  margin-top: 7px;
  font-weight: 700;
}

.ml-story-lab {
  width: var(--page);
  margin: 0 auto;
  padding: clamp(28px, 5vw, 56px);
}

.ml-story-result {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  align-items: center;
}

.ml-story-result .ml-feedback { margin-bottom: 0; }

.ml-zoom-svg .ml-marker { fill: var(--ml-cinnabar); stroke: var(--text); stroke-width: 3; }
.ml-zoom-svg .ml-marker--gold { fill: var(--ml-gold); }

.ml-rate-readout {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px 22px;
  align-items: baseline;
  margin-top: 20px;
  padding: 20px;
  border-left: 3px solid var(--ml-cinnabar);
  background: color-mix(in srgb, var(--surface-strong) 78%, transparent);
}

.ml-rate-readout span { grid-column: 1 / -1; }
.ml-rate-readout strong { font: 400 44px var(--ml-math); }
.ml-rate-readout b { color: var(--muted); font-size: 13px; }

.ml-equation-key {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 24px;
}

.ml-equation-key span {
  padding: 12px 14px;
  border-left: 2px solid var(--line-strong);
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
}

.ml-equation-key b {
  display: block;
  margin-bottom: 4px;
  color: var(--text);
  font-size: 13px;
}

.ml-interval-reader {
  display: grid;
  gap: 16px;
  margin: 26px 0 32px;
  padding: 22px;
  border: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface-strong) 70%, transparent);
}

.ml-interval-reader > div:first-child {
  display: flex;
  gap: 12px 24px;
  align-items: baseline;
  justify-content: space-between;
}

.ml-interval-reader > div:first-child strong {
  font-family: var(--ml-serif);
  font-size: 20px;
}

.ml-interval-reader > div:first-child span,
.ml-interval-reader > p {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.55;
}

.ml-distance-intervals {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
}

.ml-distance-interval {
  display: grid;
  gap: 10px;
  min-width: 0;
  padding: 12px;
  border: 1px solid var(--line);
  transition: border-color 220ms ease, background 220ms ease, transform 220ms var(--ease);
}

.ml-distance-interval > span {
  color: var(--muted);
  font: 700 11px var(--mono);
}

.ml-distance-interval > i {
  position: relative;
  display: block;
  width: calc(100% * var(--interval-distance));
  min-width: 5px;
  height: 3px;
  margin: 8px 0;
  background: var(--ml-cinnabar);
  transform-origin: left;
  transition: width 500ms var(--ease), background 220ms ease;
}

.ml-distance-interval > i::after {
  position: absolute;
  top: -4px;
  right: -5px;
  width: 11px;
  height: 11px;
  border: 2px solid var(--surface);
  border-radius: 50%;
  background: inherit;
  content: "";
}

.ml-distance-interval > strong {
  font: 400 18px var(--ml-math);
}

.ml-distance-interval.is-complete,
.ml-distance-interval.is-current {
  border-color: var(--ml-gold);
  background: color-mix(in srgb, var(--ml-gold) 11%, var(--surface));
}

.ml-distance-interval.is-current { transform: translateY(-4px); }

.ml-interval-reader > p { margin: 0; }

.ml-practice-section {
  padding: clamp(72px, 9vw, 118px) 0;
  border-top: 1px solid var(--line);
}

.ml-practice {
  display: grid;
  grid-template-columns: minmax(220px, 0.48fr) minmax(0, 1.52fr);
  gap: clamp(34px, 7vw, 92px);
  align-items: start;
}

.ml-practice-heading {
  position: sticky;
  top: 116px;
}

.ml-practice-heading > span {
  display: block;
  margin-bottom: 12px;
  color: var(--ml-cinnabar);
  font-size: 13px;
  font-weight: 800;
}

.ml-practice-heading h2 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(34px, 4vw, 54px);
  letter-spacing: -0.04em;
  line-height: 1.08;
}

.ml-practice-heading p {
  max-width: 28em;
  margin: 18px 0 0;
  color: var(--muted);
  line-height: 1.65;
}

.ml-practice form,
.ml-practice-questions {
  display: grid;
  gap: 0;
}

.ml-practice-question {
  min-width: 0;
  margin: 0;
  padding: 26px 0 30px;
  border: 0;
  border-bottom: 1px solid var(--line);
}

.ml-practice-question:first-child { padding-top: 0; }

.ml-practice-question legend {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 12px;
  width: 100%;
  padding: 0;
}

.ml-practice-question legend span {
  padding-top: 4px;
  color: var(--ml-gold);
  font: 700 11px var(--mono);
}

.ml-practice-question legend strong {
  font-family: var(--ml-serif);
  font-size: clamp(19px, 2vw, 24px);
  line-height: 1.35;
}

.ml-practice-choices {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 9px;
  margin: 18px 0 0 46px;
}

.ml-practice-choices label {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 10px;
  align-items: center;
  min-width: 0;
  padding: 11px 12px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: border-color 180ms ease, background 180ms ease, transform 180ms var(--ease);
}

.ml-practice-choices label:hover,
.ml-practice-choices label:focus-within {
  border-color: var(--ml-cinnabar);
  transform: translateY(-2px);
}

.ml-practice-choices input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.ml-practice-choices label > span {
  display: grid;
  place-items: center;
  width: 28px;
  height: 28px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  color: var(--muted);
  font: 700 11px var(--mono);
}

.ml-practice-choices label > b {
  font-size: 13px;
  line-height: 1.45;
}

.ml-practice-choices label:has(input:checked) {
  border-color: var(--ml-cinnabar);
  background: color-mix(in srgb, var(--ml-cinnabar) 10%, var(--surface));
}

.ml-practice-choices label:has(input:focus-visible) {
  outline: 3px solid color-mix(in srgb, var(--ml-cinnabar) 38%, transparent);
  outline-offset: 3px;
}

.ml-practice-choices label.is-correct {
  border-color: var(--ml-gold);
  background: color-mix(in srgb, var(--ml-gold) 15%, var(--surface));
}

.ml-practice-choices label.is-wrong {
  border-color: var(--ml-cinnabar);
  background: color-mix(in srgb, var(--ml-cinnabar) 16%, var(--surface));
}

.ml-practice-status {
  margin: 22px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.ml-practice-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

.ml-practice-actions .ml-button[hidden],
.ml-practice-explanations[hidden] {
  display: none !important;
}

.ml-practice-explanations {
  display: grid;
  gap: 24px;
  margin-top: 38px;
  padding: clamp(22px, 4vw, 36px);
  border-left: 3px solid var(--ml-gold);
  background: color-mix(in srgb, var(--surface-strong) 78%, transparent);
}

.ml-practice-explanations h3 {
  margin: 0;
  font-family: var(--ml-serif);
  font-size: clamp(28px, 3vw, 40px);
}

.ml-practice-answer-grid {
  display: grid;
  gap: 22px;
}

.ml-practice-answer-grid article + article {
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.ml-practice-answer-grid h4 {
  margin: 0;
  color: var(--text);
  font-size: 15px;
  line-height: 1.45;
}

.ml-practice-answer-grid p {
  max-width: 68ch;
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

@media (max-width: 1120px) {
  .ml-lesson-hero--play,
  .ml-connection-layout,
  .ml-lab-split,
  .ml-deck-layout,
  .ml-evidence-lab {
    grid-template-columns: 1fr;
  }

  .ml-practice {
    grid-template-columns: 1fr;
  }

  .ml-practice-heading { position: static; }

  .ml-lesson-hero--play .ml-hero-copy > p:not(.ml-kicker) {
    max-width: 32em;
  }

  .ml-loop-lab {
    grid-template-columns: 1fr 1.2fr;
  }

  .ml-evidence-lab .ml-loop-controls {
    grid-column: 1;
  }
}

@media (max-width: 760px) {
  .ml-section[id] { scroll-margin-top: 138px; }
  .ml-lesson-hero--play {
    gap: 30px;
    padding-top: 124px;
  }

  .ml-lesson-hero--play .ml-hero-copy h1 {
    font-size: clamp(42px, 13vw, 58px);
  }

  .ml-connection-layout,
  .ml-loop-lab,
  .ml-lab-split,
  .ml-deck-layout,
  .ml-evidence-lab,
  .ml-question-pair,
  .ml-rule-formula {
    grid-template-columns: 1fr;
  }

  .ml-loop-lab .ml-loop-controls {
    grid-column: 1;
  }

  .ml-loop-stage {
    min-height: 320px;
  }

  .ml-loop-orbit {
    width: 210px;
    height: 210px;
  }

  .ml-loop-orbit span { transform: rotate(var(--orbit-angle)) translateX(105px); }
  .ml-loop-stage[data-loop-index="1"] .ml-loop-orbit span { transform: rotate(calc(var(--orbit-angle, 0deg) + 90deg)) translateX(105px); }
  .ml-loop-stage[data-loop-index="2"] .ml-loop-orbit span { transform: rotate(calc(var(--orbit-angle, 0deg) + 180deg)) translateX(105px); }
  .ml-loop-stage[data-loop-index="3"] .ml-loop-orbit span { transform: rotate(calc(var(--orbit-angle, 0deg) + 270deg)) translateX(105px); }

  .ml-connection-readouts,
  .ml-mini-graphs,
  .ml-distance-intervals,
  .ml-equation-key,
  .ml-practice-choices {
    grid-template-columns: 1fr;
  }

  .ml-interval-reader > div:first-child {
    display: grid;
  }

  .ml-distance-interval {
    grid-template-columns: 58px 1fr auto;
    align-items: center;
  }

  .ml-distance-interval > i {
    margin: 0;
  }

  .ml-practice-choices { margin-left: 0; }

  .ml-curiosity-band {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .ml-predict-row {
    grid-template-columns: 1fr 1fr;
  }

  .ml-predict-row > span { grid-column: 1 / -1; }

  .ml-balance-v2 { height: 230px; }
  .ml-balance-v2-beam { left: 4%; width: 92%; }
  .ml-balance-v2-pan { width: 46%; }
  .ml-balance-v2-pan--left { left: -2%; }
  .ml-balance-v2-pan--right { right: -2%; }
  .ml-unit-token { width: 22px; height: 22px; }
  .ml-variable-token { width: 34px; height: 25px; }

  .ml-scanner-stage,
  .ml-formula-deck,
  .ml-angle-assembly,
  .ml-zoom-stage {
    padding: 20px;
  }

  .ml-tower-field { height: 250px; gap: 14px; }
  .ml-number-tower { height: 220px; }
  .ml-number-tower i { height: 190px; }

  .ml-rule-formula b { text-align: center; }

  .ml-question-pair {
    gap: 20px;
  }

  .ml-angle-dashboard {
    grid-template-columns: repeat(2, 1fr);
  }

  .ml-angle-assembly {
    min-height: 550px;
  }

  .ml-proof-triangle { right: 5%; left: 5%; }
  .ml-angle-piece { width: 110px; height: 110px; }
  .ml-angle-piece--a { left: 5%; }
  .ml-angle-piece--b { right: 5%; }
  .ml-angle-piece--c { left: calc(50% - 55px); }

  .ml-straight-angle { right: 5%; left: 5%; }

  .ml-story-result {
    grid-template-columns: 1fr;
  }

  .ml-rate-readout strong { font-size: 36px; }
}

@media (prefers-reduced-motion: reduce) {
  .ml-enter,
  .ml-reveal {
    opacity: 1;
    transform: none;
    animation: none;
    transition: none;
  }

  .ml-balance-v2-beam,
  .ml-unit-token,
  .ml-variable-token,
  .ml-number-tower i,
  .ml-angle-piece,
  .ml-straight-angle,
  .ml-proof-triangle,
  .ml-traveller,
  .ml-analysis-svg .ml-curve,
  .ml-mini-graphs button,
  .ml-distance-interval,
  .ml-distance-interval > i,
  .ml-practice-choices label,
  .ml-loop-orbit span,
  .ml-loop-stage strong,
  .ml-loop-stage p,
  .ml-connection-readouts div {
    animation: none !important;
    transition: none !important;
  }
}

.ml-road-track .ml-road-checkpoints b {
  top: -26px;
  left: 50%;
  transform: translateX(-50%);
}

.ml-road-track .ml-road-checkpoints > span:first-child b {
  right: auto;
  left: 0;
  transform: none;
}

.ml-road-track .ml-road-checkpoints > span:last-child b {
  right: 0;
  left: auto;
  transform: none;
}

.ml-road-track .ml-road-checkpoints > span.is-stacked b { top: -42px; }

@media (max-width: 760px) {
  .ml-road-track .ml-road-checkpoints b { display: none; }
}

.ml-button:disabled,
.ml-choice:disabled,
.ml-preset:disabled {
  cursor: not-allowed;
  opacity: .48;
  transform: none;
}

/* Lesson 2: rules, transformations, and accumulation. */
.ml-rule-experiment,
.ml-rigid-experiment,
.ml-accumulation-experiment {
  display: grid;
  gap: 18px;
  margin-top: 20px;
}

.ml-rule-experiment[hidden],
.ml-rigid-experiment[hidden],
.ml-accumulation-experiment[hidden],
.ml-reverse-stage [hidden] {
  display: none;
}

.ml-rule-machines {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.ml-rule-machines > div {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 8px 14px;
  align-items: center;
  padding: 16px;
  border: 1px solid var(--line);
  background: var(--surface);
}

.ml-rule-machines span {
  color: var(--ml-gold);
  font: 700 10px/1 var(--mono);
  letter-spacing: .1em;
  text-transform: uppercase;
}

.ml-rule-machines b {
  justify-self: end;
  font: 700 13px/1 var(--mono);
}

.ml-rule-machines i {
  color: var(--muted);
  font: normal 13px/1.4 var(--ml-sans);
}

.ml-rule-machines strong {
  justify-self: end;
  font: 600 28px/1 var(--ml-math);
}

.ml-linked-rule-grid,
.ml-flow-linked-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(150px, .65fr);
  gap: 14px;
}

.ml-rule-svg,
.ml-transform-svg,
.ml-compose-svg,
.ml-symmetry-svg,
.ml-flow-svg,
.ml-rectangle-svg,
.ml-total-svg {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  background:
    linear-gradient(color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    linear-gradient(90deg, color-mix(in srgb, var(--text) 5%, transparent) 1px, transparent 1px),
    var(--surface-strong);
  background-size: 32px 32px;
}

.ml-rule-svg .ml-axis,
.ml-compose-svg .ml-axis,
.ml-flow-svg .ml-axis,
.ml-rectangle-svg .ml-axis,
.ml-total-svg .ml-axis {
  stroke: var(--line-strong);
  stroke-width: 2;
}

.ml-rule-svg text,
.ml-compose-svg text,
.ml-flow-svg text,
.ml-rectangle-svg text,
.ml-total-svg text {
  fill: var(--muted);
  font: 13px var(--ml-sans);
}

.ml-rule-line,
.ml-flow-curve,
.ml-rectangle-curve,
.ml-total-cumulative {
  fill: none;
  stroke: var(--ml-cinnabar);
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 4;
}

.ml-rule-line--b {
  stroke: var(--ml-gold);
  stroke-dasharray: 8 6;
  stroke-width: 3;
}

.ml-rule-point {
  fill: var(--surface-strong);
  stroke: var(--ml-cinnabar);
  stroke-width: 4;
}

.ml-rule-point--b,
.ml-rule-point--gold {
  stroke: var(--ml-gold);
}

.ml-builder-stage,
.ml-reverse-stage,
.ml-compose-stage,
.ml-symmetry-stage,
.ml-rectangle-stage,
.ml-total-stage {
  display: grid;
  gap: 18px;
  padding: clamp(20px, 3vw, 32px);
  border: 1px solid var(--line);
  background: var(--ml-panel);
}

.ml-builder-formula {
  overflow-x: auto;
  color: var(--text);
  font: 600 clamp(34px, 5vw, 56px)/1.2 var(--ml-math);
  text-align: center;
  white-space: nowrap;
}

.ml-builder-controls {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
}

.ml-builder-table {
  overflow: auto;
  max-height: 190px;
  border: 1px solid var(--line);
  background: var(--surface);
}

.ml-reverse-chain {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr;
  gap: 8px;
  align-items: center;
}

.ml-reverse-chain > div {
  display: grid;
  min-height: 116px;
  padding: 14px;
  place-items: center;
  border: 1px solid var(--line);
  background: var(--surface);
  opacity: .28;
  transform: translateY(8px);
  transition: opacity 260ms ease, transform 260ms var(--ease), border-color 260ms ease;
}

.ml-reverse-chain > div.is-active {
  border-color: var(--ml-gold);
  opacity: 1;
  transform: none;
}

.ml-reverse-chain span {
  color: var(--muted);
  font: 700 10px/1 var(--mono);
  text-align: center;
  text-transform: uppercase;
}

.ml-reverse-chain strong {
  font: 600 32px/1 var(--ml-math);
}

.ml-reverse-chain > i {
  color: var(--ml-cinnabar);
  font: 700 10px/1.35 var(--mono);
  text-align: center;
}

.ml-transform-svg defs path {
  stroke: color-mix(in srgb, var(--text) 7%, transparent);
}

.ml-transform-original {
  fill: transparent;
  stroke: var(--muted);
  stroke-dasharray: 8 7;
  stroke-width: 2;
}

.ml-transform-image {
  fill: color-mix(in srgb, var(--ml-cinnabar) 18%, transparent);
  stroke: var(--ml-cinnabar);
  stroke-linejoin: round;
  stroke-width: 4;
}

[data-rigid-image] {
  transform-origin: 270px 190px;
  transition: transform 320ms var(--ease);
}

[data-rigid-image] circle {
  fill: var(--ml-gold);
}

.ml-mirror-axis,
.ml-symmetry-axis {
  stroke: var(--ml-gold);
  stroke-dasharray: 7 7;
  stroke-width: 3;
}

.ml-invariant-dashboard,
.ml-compose-readout,
.ml-accumulation-readout,
.ml-rectangle-readout,
.ml-total-readout {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
}

.ml-compose-readout,
.ml-accumulation-readout,
.ml-rectangle-readout,
.ml-total-readout {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.ml-invariant-dashboard div,
.ml-compose-readout div,
.ml-accumulation-readout div,
.ml-rectangle-readout div,
.ml-total-readout div {
  min-width: 0;
  padding: 12px;
  border-left: 2px solid var(--line-strong);
  background: color-mix(in srgb, var(--surface) 70%, transparent);
}

.ml-invariant-dashboard span,
.ml-compose-readout span,
.ml-accumulation-readout span,
.ml-rectangle-readout span,
.ml-total-readout span {
  display: block;
  color: var(--muted);
  font: 700 10px/1.3 var(--mono);
  text-transform: uppercase;
}

.ml-invariant-dashboard strong,
.ml-compose-readout strong,
.ml-accumulation-readout strong,
.ml-rectangle-readout strong,
.ml-total-readout strong {
  display: block;
  overflow-wrap: anywhere;
  margin-top: 7px;
  font: 600 15px/1.35 var(--ml-math);
}

.ml-compose-path {
  fill: none;
  stroke: var(--ml-gold);
  stroke-dasharray: 8 6;
  stroke-width: 4;
  transition: d 320ms var(--ease);
}

.ml-compose-start {
  fill: var(--surface-strong);
  stroke: var(--text);
  stroke-width: 3;
}

.ml-compose-first,
.ml-compose-final {
  fill: var(--surface-strong);
  opacity: 0;
  stroke: var(--ml-cinnabar);
  stroke-width: 4;
  transition: opacity 220ms ease, cx 360ms var(--ease), cy 360ms var(--ease);
}

.ml-compose-final { stroke: var(--ml-gold); }
.ml-compose-first.is-visible,
.ml-compose-final.is-visible { opacity: 1; }

.ml-symmetry-original,
.ml-symmetry-image {
  fill: color-mix(in srgb, var(--ml-cinnabar) 15%, transparent);
  stroke: var(--ml-cinnabar);
  stroke-linejoin: round;
  stroke-width: 4;
}

.ml-symmetry-original {
  fill: transparent;
  stroke: var(--muted);
  stroke-dasharray: 7 7;
  stroke-width: 2;
}

.ml-symmetry-image {
  transition: points 360ms var(--ease), fill 220ms ease;
}

.ml-symmetry-image.is-folded {
  fill: color-mix(in srgb, var(--ml-gold) 22%, transparent);
  stroke: var(--ml-gold);
}

.ml-flow-area {
  fill: color-mix(in srgb, var(--ml-cinnabar) 24%, transparent);
  stroke: none;
}

.ml-flow-curve { stroke: var(--ml-gold); }

.ml-tank {
  position: relative;
  overflow: hidden;
  min-height: 100%;
  border: 3px solid var(--line-strong);
  border-top: 0;
  background: var(--surface);
}

.ml-tank::before {
  position: absolute;
  inset: 50% 0 auto;
  z-index: 2;
  border-top: 1px dashed var(--line-strong);
  content: "";
}

.ml-tank > span {
  position: absolute;
  right: 8px;
  z-index: 3;
  color: var(--muted);
  font: 700 10px/1 var(--mono);
}

.ml-tank > span:nth-of-type(1) { top: 8px; }
.ml-tank > span:nth-of-type(2) { top: calc(50% - 5px); }
.ml-tank > span:nth-of-type(3) { bottom: 8px; }

.ml-tank-fill {
  position: absolute;
  inset: 0;
  overflow: hidden;
  background: linear-gradient(180deg, color-mix(in srgb, var(--ml-cinnabar) 52%, transparent), color-mix(in srgb, var(--ml-cinnabar) 78%, var(--surface)));
  transform: scaleY(var(--tank-level, 0));
  transform-origin: bottom;
  transition: transform 180ms linear;
}

.ml-tank-fill i {
  position: absolute;
  top: -7px;
  width: 42px;
  height: 14px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--ml-gold) 32%, transparent);
  animation: ml-water-drift 2.8s ease-in-out infinite alternate;
}

.ml-tank-fill i:nth-child(1) { left: 5%; }
.ml-tank-fill i:nth-child(2) { left: 38%; animation-delay: -.8s; }
.ml-tank-fill i:nth-child(3) { right: 4%; animation-delay: -1.5s; }

@keyframes ml-water-drift {
  to { transform: translateX(20px) scaleX(1.25); }
}

[data-rectangle-group] rect {
  fill: color-mix(in srgb, var(--ml-cinnabar) 18%, transparent);
  stroke: color-mix(in srgb, var(--ml-cinnabar) 78%, var(--text));
  stroke-width: 1;
}

.ml-rectangle-curve { stroke: var(--ml-gold); }

.ml-rate-sliders {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
}

.ml-rate-sliders label {
  display: grid;
  gap: 8px;
  min-width: 0;
  padding: 10px;
  border: 1px solid var(--line);
  background: var(--surface);
}

.ml-rate-sliders span {
  overflow: hidden;
  color: var(--muted);
  font: 700 9px/1.2 var(--mono);
  text-overflow: ellipsis;
  text-transform: uppercase;
  white-space: nowrap;
}

.ml-rate-sliders output {
  font: 700 14px/1 var(--mono);
  text-align: center;
}

.ml-rate-sliders input {
  width: 100%;
  accent-color: var(--ml-cinnabar);
}

[data-total-bars] rect {
  fill: color-mix(in srgb, var(--ml-cinnabar) 38%, transparent);
  stroke: var(--ml-cinnabar);
  stroke-width: 1;
}

.ml-total-cumulative {
  stroke: var(--ml-gold);
  stroke-width: 5;
}

.ml-course-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  align-self: end;
  margin-top: auto;
}

.ml-course-actions .ml-course-link {
  margin-top: 0;
}

.ml-course-sequence {
  display: block;
  margin: 0 0 12px;
  color: var(--muted);
  font: 700 10px/1 var(--mono);
  letter-spacing: .1em;
  text-transform: uppercase;
}

@media (max-width: 1120px) {
  .ml-builder-controls { grid-template-columns: 1fr; }
  .ml-invariant-dashboard { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  .ml-linked-rule-grid,
  .ml-flow-linked-grid { grid-template-columns: 1fr; }
  .ml-tank { min-height: 240px; }
}

@media (max-width: 760px) {
  .ml-rule-machines,
  .ml-invariant-dashboard,
  .ml-compose-readout,
  .ml-accumulation-readout,
  .ml-rectangle-readout,
  .ml-total-readout { grid-template-columns: 1fr; }

  .ml-reverse-chain {
    grid-template-columns: 1fr;
  }

  .ml-reverse-chain > div { min-height: 86px; }
  .ml-reverse-chain > i { padding: 2px 0; }
  .ml-rate-sliders { grid-template-columns: 1fr; }
  .ml-rate-sliders label { grid-template-columns: 80px 1fr 34px; align-items: center; }
  .ml-rate-sliders output { text-align: right; }
}

@media (prefers-reduced-motion: reduce) {
  [data-rigid-image],
  .ml-reverse-chain > div,
  .ml-compose-path,
  .ml-compose-first,
  .ml-compose-final,
  .ml-symmetry-image,
  .ml-tank-fill {
    transition: none !important;
  }

  .ml-tank-fill i { animation: none !important; }
}