:root {
  color-scheme: light;
  --paper: #f7f5ee;
  --ink: #263d36;
  --muted: #596760;
  --line: #cbd0c4;
  --teal: #236a60;
  --gold: #9a6b32;
}
* {
  box-sizing: border-box;
  min-width: 0;
}
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font:
    16px/1.65 -apple-system,
    BlinkMacSystemFont,
    "Noto Sans TC",
    sans-serif;
}
a {
  color: var(--teal);
  text-underline-offset: 4px;
}
button,
input,
select {
  font: inherit;
}
button,
select,
.file-button {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: transparent;
  color: var(--ink);
  padding: 8px 12px;
  cursor: pointer;
}
button:hover,
.file-button:hover {
  background: #e6eadd;
}
button[aria-pressed="true"],
button.selected {
  background: var(--ink);
  color: #fff;
  border-color: var(--ink);
}
button:disabled {
  opacity: 0.5;
  cursor: wait;
}
:focus-visible {
  outline: 3px solid #a15c24;
  outline-offset: 3px;
}
input[type="range"] {
  width: 100%;
  height: 44px;
  margin: 0;
  accent-color: var(--teal);
  cursor: ew-resize;
}
input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--teal);
}
input[type="text"],
input[type="number"],
input:not([type]) {
  width: 100%;
  padding: 8px;
  border: 1px solid var(--line);
  background: #fffdf6;
  border-radius: 3px;
  min-height: 44px;
}
label {
  display: block;
}
select {
  width: 100%;
  background: var(--paper);
}
summary {
  cursor: pointer;
  min-height: 44px;
  padding: 10px 0;
  font-weight: 650;
}
details {
  border-top: 1px solid var(--line);
  margin-top: 14px;
}
details p {
  font-size: 14px;
}
p {
  margin: 0 0 16px;
}
h1 {
  font-size: clamp(26px, 2.8vw, 39px);
  line-height: 1.35;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
  font-weight: 700;
  text-wrap: balance;
}
h2 {
  font-size: 22px;
  line-height: 1.4;
  margin: 30px 0 14px;
}
.skip {
  position: absolute;
  top: -100px;
  background: #fff;
  padding: 10px;
  z-index: 30;
}
.skip:focus {
  top: 0;
}
.masthead {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  padding: 18px 28px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}
.masthead > span {
  letter-spacing: 0.12em;
}
.masthead > div {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}
.lab-shell {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  max-width: 1600px;
  margin: auto;
}
.lesson-nav {
  padding: 30px 20px;
  border-right: 1px solid var(--line);
}
.lesson-nav > p {
  font-weight: 700;
}
.lesson-nav button {
  display: block;
  width: 100%;
  text-align: left;
  border: 0;
  border-radius: 0;
  margin-bottom: 4px;
  font-size: 15px;
}
.lesson-nav button[aria-pressed="true"] {
  border-left: 3px solid var(--teal);
  background: #e1e8dc;
  color: var(--ink);
}
.lesson-nav > a {
  font-size: 14px;
  display: block;
  margin-top: 20px;
}
.workspace {
  padding: 30px 32px;
}
.lesson-intro {
  max-width: 900px;
}
.lesson-intro > p:first-child {
  color: var(--gold);
  font-size: 14px;
  letter-spacing: 0.06em;
  margin-bottom: 12px;
}
.lesson-intro > p:last-child {
  max-width: 800px;
}
.experiment {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 310px;
  gap: 26px;
  margin-top: 28px;
}
.visual-column {
  min-width: 0;
}
#model {
  height: clamp(340px, 52vh, 490px);
  position: relative;
  background: #f2f0e8;
  border: 1px solid #d4d7cc;
  overflow: hidden;
}
canvas {
  display: block;
  width: 100%;
  height: 100%;
}
.bone-labels {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.bone-label {
  position: absolute;
  top: 0;
  left: 0;
  background: #263d36;
  color: white;
  font-size: 12px;
  min-width: 20px;
  text-align: center;
  border-radius: 2px;
}
.model-caption {
  position: absolute;
  top: 14px;
  left: 16px;
  right: 16px;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  font-size: 13px;
  pointer-events: none;
}
.orientation {
  position: absolute;
  bottom: 12px;
  left: 16px;
  font-size: 12px;
  color: var(--muted);
}
#model-status {
  position: absolute;
  left: 20px;
  right: 20px;
  top: 44%;
  text-align: center;
  background: var(--paper);
  padding: 12px;
  z-index: 2;
}
#model-status:empty {
  display: none;
}
.view-tools,
.presets {
  display: flex;
  gap: 7px;
  flex-wrap: wrap;
}
.view-tools {
  margin-top: 10px;
}
.view-tools button {
  font-size: 14px;
  padding: 7px 10px;
}
.small {
  font-size: 14px;
  color: var(--muted);
  margin: 8px 0 14px;
}
.readout {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  font-size: 14px;
  min-height: 48px;
  padding: 10px 0;
  border-top: 1px solid var(--line);
}
.readout strong {
  font-size: 20px;
  font-weight: 600;
}
.principle {
  background: #efeee4;
  margin-top: 8px;
}
.principle svg {
  display: block;
  width: 100%;
  max-height: 245px;
}
.control-column {
  border-left: 1px solid var(--line);
  padding-left: 24px;
}
.presets {
  margin-bottom: 20px;
}
.presets button {
  font-size: 14px;
}
.slider-row {
  margin-bottom: 16px;
}
.slider-row label,
#workbench > label {
  font-weight: 600;
  font-size: 15px;
  display: flex;
  justify-content: space-between;
  gap: 10px;
}
.slider-row output,
output {
  color: var(--teal);
  font-variant-numeric: tabular-nums;
}
.select-label {
  margin: 16px 0 8px;
  font-weight: 600;
}
.observation {
  font-size: 15px;
  background: #e7ecdf;
  padding: 16px;
  margin-top: 20px;
  border-left: 3px solid var(--teal);
}
.display-settings label,
#bone-toggles label {
  display: flex;
  gap: 9px;
  align-items: center;
  min-height: 44px;
  font-size: 14px;
  overflow-wrap: anywhere;
}
.reading {
  max-width: 900px;
  border-top: 1px solid var(--line);
  margin-top: 36px;
  padding-top: 8px;
}
.reading > p {
  font-size: 18px;
}
.reading details {
  max-width: 800px;
}
#quiz {
  margin: 24px 0;
}
.file-button {
  font-size: 14px;
  display: flex;
  align-items: center;
}
.file-button input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}
.file-button:focus-within {
  outline: 3px solid #a15c24;
}
.pivot-inputs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}
#recipe-status,
#quiz-feedback {
  font-size: 15px;
  color: var(--teal);
}
footer {
  display: flex;
  gap: 24px;
  justify-content: space-between;
  font-size: 14px;
  color: var(--muted);
  margin-top: 40px;
  padding: 24px 0;
  border-top: 1px solid var(--line);
}
[hidden] {
  display: none !important;
}
@media (min-width: 1400px) {
  .experiment {
    grid-template-columns: minmax(0, 1fr) 340px;
  }
}
@media (max-width: 1100px) {
  .lab-shell {
    grid-template-columns: 160px minmax(0, 1fr);
  }
  .workspace {
    padding: 24px 20px;
  }
  .lesson-nav {
    padding: 25px 12px;
  }
  .experiment {
    grid-template-columns: minmax(0, 1fr) 270px;
    gap: 18px;
  }
  .control-column {
    padding-left: 18px;
  }
  .masthead > span {
    display: none;
  }
}
@media (max-width: 850px) {
  .lab-shell {
    display: block;
  }
  .lesson-nav {
    border-right: 0;
    border-bottom: 1px solid var(--line);
    padding: 14px 20px;
  }
  .lesson-nav > p,
  .lesson-nav > a {
    display: none;
  }
  #lesson-buttons {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
  }
  .lesson-nav button {
    width: auto;
    display: inline-block;
    font-size: 14px;
    padding: 7px 10px;
  }
  .experiment {
    grid-template-columns: minmax(0, 1fr) 270px;
  }
  #model {
    height: 380px;
  }
  .masthead {
    padding: 14px 20px;
  }
}
@media (max-width: 650px) {
  .experiment {
    grid-template-columns: 1fr;
    gap: 18px;
    margin-top: 20px;
  }
  .control-column {
    border-left: 0;
    padding-left: 0;
  }
  .workspace {
    padding: 22px 20px;
  }
  .masthead {
    align-items: flex-start;
    gap: 12px;
    font-size: 13px;
  }
  .masthead > div {
    gap: 8px;
    justify-content: flex-end;
  }
  .lesson-nav {
    padding: 10px 15px;
  }
  h1 {
    font-size: 28px;
    max-width: 18em;
  }
  #model {
    height: 360px;
  }
  .model-caption {
    font-size: 12px;
  }
  .principle svg {
    max-height: 220px;
  }
  .reading {
    margin-top: 26px;
  }
  .reading > p {
    font-size: 17px;
  }
  footer {
    display: block;
  }
  footer a {
    display: block;
    margin-top: 10px;
  }
  .presets {
    margin-bottom: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  * {
    scroll-behavior: auto !important;
  }
}
@media print {
  .lesson-nav,
  .control-column,
  .view-tools,
  .masthead {
    display: none;
  }
  .lab-shell,
  .experiment {
    display: block;
  }
  .workspace {
    padding: 0;
  }
  .reading details {
    display: block;
  }
}

.mobile-nav {
  display: none;
}
@media (max-width: 650px) {
  .mobile-nav {
    display: flex;
    gap: 12px;
    align-items: center;
    font-size: 14px;
    font-weight: 600;
  }
  .mobile-nav select {
    flex: 1;
    width: auto;
  }
  .lesson-nav #lesson-buttons,
  .lesson-nav #workbench-button {
    display: none;
  }
  .lesson-nav {
    padding: 12px 20px;
  }
  .experiment {
    display: flex;
    flex-direction: column;
  }
  .visual-column {
    display: contents;
  }
  #model {
    position: sticky;
    top: 0;
    z-index: 3;
    height: 300px;
    flex-shrink: 0;
    order: 0;
  }
  .view-tools {
    order: 1;
  }
  .visual-column > .small {
    order: 2;
  }
  .control-column {
    order: 3;
  }
  .readout {
    order: 4;
  }
  .principle {
    order: 5;
  }
}

.quick-control {
  display: none;
}
@media (max-width: 650px) {
  .quick-control {
    display: block;
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 4;
    padding: 8px 14px;
    background: #f7f5eef2;
  }
  .quick-control .slider-row {
    margin: 0;
  }
  .quick-control label {
    font-size: 14px;
  }
  .quick-control input {
    height: 44px;
  }
  .orientation {
    bottom: 86px;
  }
  #model {
    height: 350px;
  }
  .masthead {
    flex-wrap: wrap;
  }
  .masthead > div {
    justify-content: flex-start;
  }
}