:root {
  color-scheme: light;
  --body-top: #dadad4;
  --body-bottom: #cdcec8;
  --chassis: #ecebe5;
  --surface: #f5f4ee;
  --surface-raised: #faf9f4;
  --surface-soft: #e6e5df;
  --screen: #e8e7df;
  --ink: #1d1e1a;
  --muted: #70726a;
  --hairline: #c3c4bc;
  --line-strong: #9fa099;
  --orange: #f36b43;
  --orange-deep: #bd4828;
  --orange-soft: #f7ddd3;
  --blue: #78a5ca;
  --blue-soft: #dce8f0;
  --yellow: #e8ca58;
  --yellow-soft: #f4ebc6;
  --green: #70a084;
  --danger: #c84d42;
  --danger-soft: #f3d8d3;
  --success: #4f896d;
  --accent: var(--orange);
  --accent-soft: var(--orange-soft);
  --diagram-fill: #eee2a9;
  --diagram-stroke: #a98e2c;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  min-width: 320px;
  background: var(--body-bottom);
}

body {
  margin: 0;
  min-height: 100vh;
  padding: 22px 0 36px;
  color: var(--ink);
  background: linear-gradient(180deg, var(--body-top), var(--body-bottom));
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
  font-variant-numeric: tabular-nums;
  font-weight: 400;
}

.katex {
  font-size: 1em;
}

.math-inline {
  display: inline-block;
  white-space: nowrap;
}

.math-inline .katex {
  font-size: 1.02em;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

button:focus-visible,
input:focus-visible,
summary:focus-visible {
  outline: 3px solid rgba(88, 143, 187, 0.55);
  outline-offset: 3px;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

.page-shell {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  border: 1px solid rgba(104, 106, 99, 0.42);
  border-radius: 18px;
  padding: 26px;
  background: var(--chassis);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.82) inset,
    0 26px 70px rgba(54, 56, 51, 0.16),
    0 2px 5px rgba(54, 56, 51, 0.08);
}

.hero {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 20px;
  border-bottom: 1px solid var(--hairline);
  padding: 1px 2px 20px;
}

.brand-lockup {
  min-width: 0;
}

h1 {
  margin-bottom: 0;
  font-size: clamp(1.65rem, 3.2vw, 2.35rem);
  font-weight: 500;
  letter-spacing: -0.055em;
  line-height: 0.96;
}

h1 span {
  color: var(--muted);
  font-weight: 400;
}

.header-actions {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 12px;
}

.language-switch {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  color: var(--hairline);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
}

.language-switch button {
  border: 0;
  border-bottom: 1px solid transparent;
  padding: 3px 2px 2px;
  color: var(--muted);
  background: transparent;
}

.language-switch button:hover {
  color: var(--ink);
}

.language-switch button[aria-pressed="true"] {
  border-bottom-color: var(--orange);
  color: var(--ink);
}

.about-button {
  display: grid;
  width: 32px;
  height: 32px;
  flex: 0 0 auto;
  place-items: center;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  padding: 0;
  color: var(--muted);
  background: var(--surface-raised);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.82) inset,
    0 1px 2px rgba(53, 55, 50, 0.08);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.82rem;
  font-weight: 500;
}

.about-button:hover {
  color: var(--ink);
  background: #fffef9;
}

.input-panel {
  overflow: hidden;
  border: 1px solid var(--hairline);
  border-radius: 12px;
  background: var(--surface);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.9) inset,
    0 7px 20px rgba(65, 67, 61, 0.055);
}

.word-form {
  padding: 15px 16px 12px;
}

.module-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
  color: var(--ink);
  font-size: 0.72rem;
  font-weight: 500;
}

.module-spec {
  color: var(--muted);
  font-weight: 400;
}

.input-row {
  display: flex;
  gap: 10px;
}

#word-input {
  min-width: 0;
  flex: 1;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  padding: 13px 14px;
  outline: none;
  color: var(--ink);
  background: var(--surface-raised);
  box-shadow:
    0 1px 2px rgba(45, 47, 42, 0.07) inset,
    0 1px 0 rgba(255, 255, 255, 0.76);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 1rem;
  letter-spacing: 0.07em;
  transition: border-color 120ms ease, box-shadow 120ms ease;
}

#word-input:focus {
  border-color: #5e8fb6;
  box-shadow:
    0 0 0 3px rgba(120, 165, 202, 0.2),
    0 1px 2px rgba(45, 47, 42, 0.07) inset;
}

#word-input.invalid {
  border-color: var(--danger);
  box-shadow: 0 0 0 3px rgba(200, 77, 66, 0.14);
}

#analyze-button {
  display: inline-flex;
  min-width: 112px;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  border: 1px solid var(--orange-deep);
  border-radius: 8px;
  padding: 12px 14px;
  color: #2a1a14;
  background: var(--orange);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.34) inset,
    0 2px 0 #a93d20,
    0 4px 9px rgba(120, 54, 32, 0.14);
  font-size: 0.76rem;
  font-weight: 500;
  transition: transform 80ms ease, box-shadow 80ms ease, filter 100ms ease;
}

#analyze-button:hover {
  filter: saturate(1.05) brightness(1.025);
}

#analyze-button:active {
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.24) inset,
    0 1px 0 #a93d20;
  transform: translateY(1px);
}

#analyze-button:disabled {
  cursor: wait;
  filter: saturate(0.5);
  opacity: 0.65;
}

.validation-message {
  display: flex;
  min-height: 18px;
  align-items: center;
  gap: 7px;
  margin-top: 9px;
  color: var(--muted);
  font-size: 0.7rem;
}

.validation-message::before {
  width: 6px;
  height: 6px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--yellow);
  box-shadow: 0 0 0 1px rgba(102, 89, 34, 0.35);
  content: "";
}

.validation-message.error {
  color: var(--danger);
}

.validation-message.error::before {
  background: var(--danger);
}

.validation-message.success {
  color: var(--success);
}

.validation-message.success::before {
  background: var(--green);
}

.random-panel {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  border-top: 1px solid var(--hairline);
  padding: 11px 16px 12px;
  background: rgba(226, 225, 218, 0.48);
  font-size: 0.7rem;
}

.random-panel button,
.quiet-button,
.copy-button {
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 6px 9px;
  color: var(--ink);
  background: var(--surface-raised);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.82) inset,
    0 1px 2px rgba(53, 55, 50, 0.08);
  font-size: 0.7rem;
  transition: background 100ms ease, transform 80ms ease, box-shadow 80ms ease;
}

.random-panel button:hover,
.quiet-button:hover,
.copy-button:hover {
  background: #fffef9;
}

.random-panel button:active,
.quiet-button:active,
.copy-button:active {
  box-shadow: 0 1px 1px rgba(53, 55, 50, 0.08) inset;
  transform: translateY(1px);
}

.random-panel button:disabled {
  cursor: wait;
  opacity: 0.55;
}

.random-example {
  display: flex;
  align-items: center;
  gap: 11px;
}

.random-conditions {
  display: flex;
  gap: 6px;
  align-items: center;
}

.random-example label {
  color: var(--muted);
}

#random-g,
#random-a {
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 5px 7px;
  color: var(--ink);
  background: var(--surface-raised);
  box-shadow: 0 1px 2px rgba(45, 47, 42, 0.055) inset;
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
}

#random-g {
  width: 62px;
}

#random-a {
  width: 82px;
}

#random-g[aria-invalid="true"],
#random-a[aria-invalid="true"] {
  border-color: var(--danger);
  box-shadow: 0 0 0 2px rgba(200, 77, 66, 0.13);
}

#random-a::placeholder {
  color: #8b8c85;
  font-size: 0.7rem;
}

#random-button {
  border-color: #aa9136;
  background: var(--yellow);
}

.result-section {
  margin-top: 27px;
}

.result-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  border-bottom: 1px solid var(--hairline);
  padding: 0 2px 9px;
}

.result-heading h2 {
  margin-bottom: 0;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.01em;
}

.word-summary {
  max-width: 74%;
  overflow: auto;
  color: var(--muted);
  font-size: 0.7rem;
  white-space: nowrap;
}

.forest-toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-start;
  gap: 10px 18px;
  padding: 10px 2px 3px;
}

.forest-toolbar.grid-mode .zoom-controls,
.forest-toolbar.grid-mode #shuffle-button {
  display: none;
}

.toolbar-group {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.toolbar-label {
  color: var(--muted);
  font-size: 0.7rem;
}

.icon-button {
  display: grid;
  width: 30px;
  height: 30px;
  line-height: 0;
  place-items: center;
  padding: 0;
}

.control-icon {
  display: block;
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.7;
}

.segmented-control {
  display: inline-flex;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: 7px;
  background: var(--surface-raised);
  box-shadow: 0 1px 2px rgba(53, 55, 50, 0.07) inset;
}

.segmented-control button {
  border: 0;
  border-right: 1px solid var(--hairline);
  padding: 6px 10px;
  color: var(--muted);
  background: transparent;
  font-size: 0.7rem;
}

.segmented-control button:last-child {
  border-right: 0;
}

.segmented-control button.active {
  color: #18212a;
  background: var(--blue);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.28) inset;
}

.quiet-button {
  box-shadow: none;
  padding: 6px 9px;
}

#shuffle-button {
  border-color: #b39b45;
  background: var(--yellow-soft);
}

#flip-button.active {
  border-color: #7897ad;
  background: var(--blue-soft);
}

.quiet-button:disabled {
  cursor: default;
  opacity: 0.4;
}

.zoom-range {
  width: clamp(140px, 19vw, 220px);
  height: 18px;
  margin: 0;
  appearance: none;
  background: transparent;
  cursor: pointer;
}

.zoom-range:disabled {
  cursor: default;
  filter: saturate(0.35);
  opacity: 0.48;
}

.zoom-range::-webkit-slider-runnable-track {
  height: 4px;
  border: 1px solid #898b84;
  border-radius: 999px;
  background: #c9cac3;
  box-shadow: 0 1px 1px rgba(55, 57, 52, 0.13) inset;
}

.zoom-range::-webkit-slider-thumb {
  width: 17px;
  height: 17px;
  margin-top: -7px;
  appearance: none;
  border: 1px solid var(--orange-deep);
  border-radius: 50%;
  background: var(--orange);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.38) inset,
    0 2px 4px rgba(65, 45, 38, 0.18);
}

.zoom-range::-moz-range-track {
  height: 4px;
  border: 1px solid #898b84;
  border-radius: 999px;
  background: #c9cac3;
}

.zoom-range::-moz-range-thumb {
  width: 17px;
  height: 17px;
  border: 1px solid var(--orange-deep);
  border-radius: 50%;
  background: var(--orange);
}

#zoom-label {
  min-width: 46px;
  color: var(--muted);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
  text-align: center;
}

.forest-frame {
  --forest-screen-background: #e9e8e1;
  --forest-grid-line: rgba(66, 75, 70, 0.035);
  --forest-glaze: rgba(255, 255, 250, 0.38);
  --forest-inner-line: #afb3ac;
  --forest-edge: #7d8882;
  --forest-label-background: #f4f2ea;
  --forest-label-line: #9da49d;
  --forest-label-ink: #343b37;
  --forest-node-ink: #252b28;
  --forest-drag-stroke: #4f7782;
  --forest-node-shadow: rgba(49, 58, 53, 0.19);
  position: relative;
  width: min(100%, 780px);
  aspect-ratio: 1;
  margin: 12px auto 0;
  overflow: hidden;
  border: 1px solid #a7aba4;
  border-radius: 16px;
  padding: 11px;
  background:
    linear-gradient(135deg, rgba(255, 255, 250, 0.48), transparent 43%, rgba(90, 105, 97, 0.06)),
    #d2d4cd;
  box-shadow:
    0 1px 0 rgba(255, 255, 252, 0.78) inset,
    0 0 0 1px rgba(255, 255, 255, 0.24),
    0 13px 29px rgba(49, 57, 52, 0.14);
}

.forest-empty,
.forest-viewport {
  border: 1px solid var(--forest-inner-line);
  border-radius: 9px;
  background:
    linear-gradient(var(--forest-grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--forest-grid-line) 1px, transparent 1px),
    linear-gradient(145deg, var(--forest-glaze), transparent 42%),
    var(--forest-screen-background);
  background-repeat: repeat, repeat, no-repeat, no-repeat;
  background-size: 28px 28px, 28px 28px, 100% 100%, auto;
  box-shadow:
    0 0 0 1px rgba(255, 255, 252, 0.48) inset,
    0 2px 8px rgba(51, 60, 55, 0.1) inset;
}

.forest-empty {
  display: grid;
  width: 100%;
  height: 100%;
  place-content: center;
  color: #777a71;
  text-align: center;
}

.forest-empty p {
  margin: 7px 0 0;
  font-size: 0.7rem;
}

.empty-mark {
  color: var(--orange);
  font-size: 2.5rem;
  font-weight: 400;
}

.forest-viewport {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
  overscroll-behavior: contain;
  cursor: grab;
  touch-action: none;
}

.forest-viewport.grid-scroll {
  overflow-x: hidden;
  overflow-y: auto;
  scrollbar-color: #8f9289 transparent;
  scrollbar-gutter: stable;
  scrollbar-width: thin;
  cursor: default;
  touch-action: pan-y;
}

.forest-viewport.grid-scroll::-webkit-scrollbar {
  width: 11px;
}

.forest-viewport.grid-scroll::-webkit-scrollbar-track {
  background: rgba(128, 131, 122, 0.08);
}

.forest-viewport.grid-scroll::-webkit-scrollbar-thumb {
  border: 3px solid transparent;
  border-radius: 999px;
  background: #8f9289;
  background-clip: padding-box;
}

.forest-viewport.panning,
.forest-viewport.node-dragging {
  cursor: grabbing;
}

.forest-sizer {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.forest-stage {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.grid-scroll .forest-sizer {
  overflow: visible;
}

.grid-scroll .forest-stage {
  position: sticky;
  top: 0;
  right: 0;
  bottom: auto;
  left: 0;
}

.forest-canvas {
  display: block;
  width: 100%;
  height: 100%;
  user-select: none;
}

.invariant-grid {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  margin-top: 24px;
  overflow: hidden;
  border: 1px solid var(--hairline);
  border-radius: 14px;
  background: var(--surface);
  box-shadow:
    0 1px 0 rgba(255, 255, 255, 0.88) inset,
    0 8px 22px rgba(59, 61, 56, 0.055);
}

.invariant-card {
  position: relative;
  min-width: 0;
  min-height: 126px;
  grid-column: span 2;
  border-right: 1px solid var(--hairline);
  padding: 17px 18px;
  background: var(--surface);
}

.invariant-card:nth-of-type(5) {
  border-right: 0;
}

.invariant-card.wide {
  grid-column: span 3;
  border-bottom: 1px solid var(--hairline);
}

.invariant-card.wide:first-child {
  border-right: 1px solid var(--hairline);
}

.invariant-card.wide:nth-child(2) {
  border-right: 0;
}

.invariant-symbol {
  position: absolute;
  top: 15px;
  right: 18px;
  color: var(--muted);
  font-size: 0.76rem;
  font-style: normal;
  font-weight: 500;
}

.invariant-value {
  position: absolute;
  right: 18px;
  bottom: 15px;
  left: 18px;
  overflow-wrap: anywhere;
  color: var(--ink);
  line-height: 1.2;
}

.invariant-value.number {
  font-size: clamp(2.35rem, 5vw, 3.25rem);
  font-weight: 500;
  letter-spacing: -0.075em;
}

.invariant-value.number .katex {
  letter-spacing: normal;
}

.a-number-card .invariant-value.number {
  bottom: 32px;
}

.invariant-card-bound {
  position: absolute;
  right: 18px;
  bottom: 12px;
  left: 18px;
  color: var(--muted);
  font-size: 0.7rem;
}

.sequence-card {
  display: flex;
  min-height: 208px;
  flex-direction: column;
  padding: 17px 18px 18px;
}

.sequence-card header {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
}

.sequence-card .invariant-symbol {
  position: static;
  color: var(--ink);
  font-size: 1.15rem;
}

.sequence-count {
  margin: 3px 0 9px;
  color: var(--muted);
  font-size: 0.7rem;
}

.sequence-value {
  position: static;
  flex: 1;
  max-height: 170px;
  overflow: auto;
  border: 1px solid var(--hairline);
  border-radius: 8px;
  padding: 11px 12px;
  color: var(--ink);
  background: var(--surface-soft);
  box-shadow:
    0 1px 2px rgba(54, 56, 51, 0.065) inset,
    0 1px 0 rgba(255, 255, 255, 0.72);
  font-size: 0.75rem;
  line-height: 1.55;
  overflow-wrap: anywhere;
  white-space: normal;
}

.sequence-value .katex {
  white-space: nowrap;
}

.lambda-card .sequence-value {
  min-height: 48px;
  max-height: 102px;
  flex: 0 1 auto;
}

.copy-button {
  border-color: var(--hairline);
  box-shadow: none;
  padding: 0;
  color: var(--muted);
  background: transparent;
}

.copy-button .copied-icon {
  display: none;
}

.copy-button.copied .copy-icon {
  display: none;
}

.copy-button.copied .copied-icon {
  display: block;
}

.young-diagram {
  margin-top: 12px;
  border-top: 1px solid var(--hairline);
  padding-top: 9px;
}

.young-diagram-heading {
  color: var(--ink);
  font-size: 0.72rem;
  font-weight: 500;
}

.young-diagram-open {
  display: block;
  width: 100%;
  border: 0;
  border-radius: 8px;
  padding: 0;
  color: inherit;
  background: transparent;
  cursor: zoom-in;
  transition: background 100ms ease;
}

.young-diagram-open:hover {
  background: rgba(230, 229, 223, 0.62);
}

#young-diagram-canvas {
  display: block;
  width: 100%;
  height: 160px;
  margin-top: 5px;
}

.about-dialog {
  width: min(620px, calc(100% - 32px));
  max-height: calc(100vh - 32px);
  overflow: auto;
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  padding: 18px;
  color: var(--ink);
  background: var(--surface);
  box-shadow: 0 28px 90px rgba(40, 42, 37, 0.26);
}

.about-dialog::backdrop {
  background: rgba(47, 49, 44, 0.46);
  backdrop-filter: blur(3px);
}

.about-dialog-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 14px;
  border-bottom: 1px solid var(--hairline);
  padding-bottom: 11px;
}

.about-dialog-heading h2 {
  margin-bottom: 0;
  font-size: 0.86rem;
  font-weight: 500;
}

.about-dialog-heading button {
  border: 1px solid var(--hairline);
  border-radius: 6px;
  color: var(--muted);
  background: transparent;
}

.about-content {
  display: grid;
  gap: 15px;
}

.about-flow {
  overflow-x: auto;
  border: 1px solid var(--hairline);
  border-radius: 8px;
  padding: 11px 12px;
  color: var(--ink);
  background: var(--surface-soft);
  font-size: 0.72rem;
  text-align: center;
  white-space: nowrap;
}

.about-flow .katex {
  font-size: 1.08em;
}

.about-content section {
  display: grid;
  gap: 5px;
}

.about-content h3 {
  margin: 0;
  color: var(--muted);
  font-size: 0.67rem;
  font-weight: 500;
  letter-spacing: 0.055em;
  text-transform: uppercase;
}

.about-content p {
  margin: 0;
  line-height: 1.55;
}

.about-scope {
  border-top: 1px solid var(--hairline);
  padding-top: 13px;
}

.young-diagram-dialog {
  width: min(920px, calc(100% - 32px));
  max-height: calc(100vh - 32px);
  overflow: auto;
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  padding: 16px;
  color: var(--ink);
  background: var(--surface);
  box-shadow: 0 28px 90px rgba(40, 42, 37, 0.26);
}

.young-diagram-dialog::backdrop {
  background: rgba(47, 49, 44, 0.46);
  backdrop-filter: blur(3px);
}

.young-diagram-dialog-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--hairline);
  padding-bottom: 10px;
}

.young-diagram-dialog-heading h2 {
  margin-bottom: 0;
  font-size: 0.82rem;
  font-weight: 500;
}

.young-diagram-dialog-heading button {
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 6px 9px;
  color: var(--ink);
  background: var(--surface-raised);
  font-size: 0.7rem;
}

.young-diagram-large-viewport {
  width: 100%;
  height: min(68vh, 640px);
  min-height: 300px;
  overflow: auto;
  border: 1px solid var(--hairline);
  border-radius: 9px;
  background: var(--surface-raised);
  scrollbar-color: #8f9289 transparent;
  scrollbar-width: thin;
}

.young-diagram-large-stage {
  --young-row-axis-width: 52px;
  --young-column-axis-height: 36px;
  display: grid;
  width: max-content;
  min-width: 100%;
  min-height: 100%;
  grid-template-columns: var(--young-row-axis-width) auto;
  grid-template-rows: var(--young-column-axis-height) auto;
  align-content: start;
  align-items: start;
}

.young-diagram-axis-corner {
  position: sticky;
  z-index: 3;
  top: 0;
  left: 0;
  display: grid;
  width: var(--young-row-axis-width);
  height: var(--young-column-axis-height);
  grid-column: 1;
  grid-row: 1;
  place-items: center;
  border-right: 1px solid var(--hairline);
  border-bottom: 1px solid var(--hairline);
  color: var(--muted);
  background: var(--surface-raised);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.66rem;
}

.young-diagram-axis {
  display: block;
  max-width: none;
  background: var(--surface-raised);
}

#young-diagram-column-axis {
  position: sticky;
  z-index: 2;
  top: 0;
  grid-column: 2;
  grid-row: 1;
}

#young-diagram-row-axis {
  position: sticky;
  z-index: 2;
  left: 0;
  grid-column: 1;
  grid-row: 2;
}

#young-diagram-large-canvas {
  display: block;
  max-width: none;
  grid-column: 2;
  grid-row: 2;
  background: var(--surface-raised);
}

.bounds-card {
  min-width: 0;
  grid-column: 1 / -1;
  border-top: 1px solid var(--hairline);
  padding: 18px;
  background: var(--surface);
}

.bounds-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px 20px;
  border-bottom: 1px solid var(--hairline);
  padding-bottom: 10px;
}

.bounds-heading h3 {
  margin-bottom: 0;
  font-size: 0.78rem;
  font-weight: 500;
}

.bounds-parameters {
  color: var(--muted);
  font-size: 0.7rem;
  text-align: right;
}

.bounds-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.bound-row {
  min-width: 0;
  padding: 17px 22px 11px 0;
}

.bound-row + .bound-row {
  border-left: 1px solid var(--hairline);
  padding-right: 0;
  padding-left: 22px;
}

.bound-row-heading {
  display: flex;
  min-height: 35px;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 16px;
}

.bound-symbol {
  color: var(--ink);
  font-size: 0.76rem;
  font-weight: 500;
}

.bound-plot {
  --marker-position: 50%;
  --interval-start: 8%;
  --interval-end: 92%;
  min-width: 0;
  padding: 28px 7px 0;
}

.bound-track {
  position: relative;
  height: 6px;
  border-radius: 999px;
  background: #d3d4cd;
  box-shadow: 0 1px 2px rgba(43, 45, 40, 0.14) inset;
}

.bound-admissible {
  position: absolute;
  top: 50%;
  left: var(--interval-start);
  width: calc(var(--interval-end) - var(--interval-start));
  height: 8px;
  border: 1px solid #9a842e;
  border-radius: inherit;
  background: var(--yellow);
  box-shadow: 0 1px 1px rgba(74, 62, 24, 0.12);
  transform: translateY(-50%);
}

.bound-end {
  position: absolute;
  top: 50%;
  z-index: 2;
  width: 8px;
  height: 8px;
  border: 1px solid #786a2c;
  border-radius: 50%;
  background: var(--surface-raised);
  transform: translate(-50%, -50%);
}

.bound-end-lower {
  left: var(--interval-start);
}

.bound-end-upper {
  left: var(--interval-end);
}

.bound-marker {
  position: absolute;
  top: 50%;
  left: var(--marker-position);
  z-index: 3;
  width: 2px;
  height: 27px;
  border-radius: 999px;
  background: var(--ink);
  transform: translate(-50%, -50%);
  transition: left 160ms ease;
}

.bound-marker::after {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 10px;
  height: 10px;
  border: 1px solid var(--orange-deep);
  border-radius: 50%;
  background: var(--orange);
  box-shadow: 0 1px 2px rgba(74, 39, 28, 0.22);
  content: "";
  transform: translate(-50%, -50%);
}

.bound-marker-label {
  position: absolute;
  bottom: 18px;
  left: 50%;
  color: var(--ink);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
  white-space: nowrap;
  transform: translateX(-50%);
}

.marker-at-lower .bound-marker-label {
  left: 0;
  transform: translateX(-1px);
}

.marker-at-upper .bound-marker-label {
  right: 0;
  left: auto;
  transform: translateX(1px);
}

.is-outside .bound-marker,
.is-outside .bound-marker::after {
  background: var(--danger);
}

.is-outside .bound-marker::after {
  border-color: #8d302a;
}

.is-outside .bound-marker-label {
  color: var(--danger);
}

.is-exact .bound-admissible {
  top: 50%;
  left: var(--interval-start);
  width: 11px;
  height: 11px;
  border: 1px solid #786a2c;
  border-radius: 50%;
  background: var(--yellow);
  transform: translate(-50%, -50%);
}

.is-exact .bound-end-lower {
  left: var(--interval-start);
}

.is-exact .bound-end-upper {
  display: none;
}

.bound-end-labels {
  position: relative;
  min-height: 15px;
  margin-top: 9px;
  color: var(--muted);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
}

.bound-end-labels span {
  position: absolute;
  top: 0;
  white-space: nowrap;
  transform: translateX(-50%);
}

.bound-end-labels span:first-child {
  left: var(--interval-start);
}

.bound-end-labels span:last-child {
  left: var(--interval-end);
}

.interval-at-left .bound-end-labels span:first-child {
  transform: translateX(0);
}

.interval-at-right .bound-end-labels span:last-child {
  transform: translateX(-100%);
}

.is-exact .bound-end-labels {
  text-align: center;
}

.bound-envelope {
  min-height: 1.4em;
  margin-top: 8px;
  color: var(--muted);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
  line-height: 1.4;
}

.bounds-observation {
  border: 1px solid rgba(172, 57, 48, 0.56);
  border-radius: 7px;
  padding: 8px 10px;
  color: #6c2822;
  background: var(--danger-soft);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.7rem;
  line-height: 1.45;
}

.bounds-observation p {
  margin-bottom: 4px;
}

.bounds-observation p:last-child {
  margin-bottom: 0;
}

.bounds-info {
  margin-top: 3px;
  border-top: 1px solid var(--hairline);
  padding-top: 8px;
  color: var(--muted);
  font-size: 0.7rem;
}

.bounds-info summary {
  width: fit-content;
  cursor: pointer;
  color: var(--muted);
}

.bounds-info-content {
  display: grid;
  gap: 7px;
  margin-top: 9px;
}

.info-formula,
.bounds-info .bound-envelope {
  margin: 0;
  color: var(--muted);
  line-height: 1.45;
}

.info-formula {
  overflow-x: auto;
  color: var(--ink);
  font-size: 0.82rem;
  white-space: nowrap;
}

.info-formula .katex {
  font-size: 1.05em;
}

.bounds-info p {
  max-width: 680px;
  margin: 1px 0 2px;
  line-height: 1.5;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  clip-path: inset(50%);
}

@media (max-width: 760px) {
  body {
    padding-top: 10px;
  }

  .page-shell {
    width: min(100% - 16px, 1120px);
    border-radius: 14px;
    padding: 18px;
  }

  .result-heading {
    align-items: start;
    flex-direction: column;
  }

  .word-summary {
    max-width: 100%;
  }

  .forest-toolbar {
    align-items: start;
    flex-direction: column;
  }

  .zoom-controls {
    width: 100%;
    flex-wrap: wrap;
  }

  .zoom-range {
    min-width: 120px;
    flex: 1 1 140px;
  }

  .invariant-card.wide {
    grid-column: 1 / -1;
    border-right: 0;
  }

  .invariant-card.wide:first-child {
    border-right: 0;
  }

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

  .bound-row,
  .bound-row + .bound-row {
    border-left: 0;
    padding-right: 0;
    padding-left: 0;
  }

  .bound-row + .bound-row {
    border-top: 1px solid var(--hairline);
  }

  .random-example {
    width: 100%;
    justify-content: flex-end;
  }
}

@media (max-width: 520px) {
  body {
    padding-bottom: 10px;
  }

  .page-shell {
    width: calc(100% - 10px);
    border-radius: 11px;
    padding: 12px;
  }

  .hero {
    margin-bottom: 14px;
    padding: 2px 1px 15px;
  }

  .module-spec {
    display: none;
  }

  .word-form {
    padding: 13px 12px 10px;
  }

  .input-row {
    flex-direction: column;
  }

  #analyze-button {
    width: 100%;
  }

  .random-panel {
    padding-right: 12px;
    padding-left: 12px;
  }

  .young-diagram-dialog {
    width: calc(100% - 12px);
    max-height: calc(100vh - 12px);
    padding: 12px;
  }

  .about-dialog {
    width: calc(100% - 12px);
    max-height: calc(100vh - 12px);
    padding: 14px;
  }

  .forest-frame {
    border-radius: 12px;
    padding: 7px;
  }

  .forest-empty,
  .forest-viewport {
    border-radius: 7px;
  }

  .invariant-card {
    padding-right: 13px;
    padding-left: 13px;
  }

  .invariant-symbol {
    right: 13px;
  }

  .invariant-value,
  .invariant-card-bound {
    right: 13px;
    left: 13px;
  }

  .bounds-card {
    padding: 14px;
  }

  .bounds-heading {
    align-items: start;
    flex-direction: column;
  }

  .bounds-parameters {
    text-align: left;
  }

  .bound-row-heading {
    min-height: 0;
    align-items: start;
    flex-direction: column;
  }

}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}