/* Hear the Shape of a Drum. Colours sampled from a photograph of a Chladni
   plate mid-experiment (Wikimedia Commons, "Quadratic Chladni plate"): blue-
   black steel, pale sand on the nodal lines, and the green sand bin as the one
   saturated colour. */

:root {
  --plate: #232524;
  --steel: #373f56;
  --rim: #8c8279;
  --head: #47505c;
  --sand: #e0e0e0;
  --green: #37885b;
  --true: #63686e;
  --bars: #d6d6d7;
  --accent: #2a7749;
  --muted: #9ca0a7;
  --serif: 'Newsreader', Georgia, serif;
  --sans: 'Figtree', 'Helvetica Neue', Arial, sans-serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: var(--plate);
  color: var(--sand);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

button, input { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--sand); outline-offset: 3px; }

.masthead {
  padding: 28px 32px 8px;
}

.masthead h1 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(30px, 4vw, 44px);
  letter-spacing: -0.01em;
  line-height: 1.1;
}

.masthead p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 16px;
}

/* ---- the bench: drum on the left, listener on the right ------------------ */

.bench {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 360px;
  gap: 20px;
  padding: 12px 32px 32px;
}

.stage {
  position: relative;
  display: flex;
  flex-direction: column;
  min-height: 560px;
  height: calc(100svh - 150px);
  max-height: 820px;
}

.canvas-wrap {
  position: relative;
  flex: 1;
  min-height: 0;
}

#view, #twins {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
  cursor: crosshair;
}

.status {
  position: absolute;
  z-index: 1;
  top: 10px;
  left: 4px;
  right: 4px;
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  pointer-events: none;
}

.hint {
  flex-basis: 100%;
  margin: 0 0 2px;
  color: var(--muted);
  font-size: 14px;
}

.tray {
  display: flex;
  align-items: center;
  gap: 10px 24px;
  flex-wrap: wrap;
  padding-top: 8px;
}

.figures {
  flex-basis: 100%;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  color: var(--sand);
  font-size: 14px;
}
.figures > div { display: flex; gap: 6px; flex-wrap: wrap; }
.figure-note {
  min-width: 36px;
  padding: 5px 9px;
  border: 1px solid #3b3e3d;
  border-radius: 8px;
  background: #2b2e2d;
  color: var(--sand);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
}
.figure-note:hover { border-color: var(--rim); }
.figure-note[aria-pressed='true'] { background: var(--accent); border-color: var(--accent); }

.examples { display: flex; gap: 8px; }

.example {
  width: 42px;
  height: 42px;
  padding: 0;
  border: 1px solid #3b3e3d;
  border-radius: 10px;
  background: #2b2e2d;
  cursor: pointer;
}
.example svg { width: 24px; height: 24px; fill: none; stroke: var(--bars); stroke-width: 1.5; stroke-linejoin: round; }
.example:hover { border-color: var(--rim); }
.example[aria-pressed='true'] { border-color: var(--sand); background: var(--head); }

.dial {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  font-size: 13px;
}

input[type='range'] {
  -webkit-appearance: none;
  appearance: none;
  width: 120px;
  height: 24px;
  background: transparent;
  cursor: pointer;
}
input[type='range']::-webkit-slider-runnable-track { height: 2px; background: var(--true); }
input[type='range']::-moz-range-track { height: 2px; background: var(--true); }
input[type='range']::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px; height: 16px; margin-top: -7px;
  border-radius: 50%;
  background: var(--sand);
}
input[type='range']::-moz-range-thumb { width: 16px; height: 16px; border: 0; border-radius: 50%; background: var(--sand); }

/* ---- the listener panel ------------------------------------------------- */

.listener {
  align-self: start;
  padding: 20px 22px 22px;
  border-radius: 14px;
  background: var(--steel);
}

.listener h2, .quiz h2, .twins h2, .essay h2 {
  margin: 0 0 12px;
  font-family: var(--serif);
  font-weight: 400;
  font-size: 24px;
  line-height: 1.2;
}

.notes { display: block; width: 100%; height: auto; }
.notes .bar { stroke: var(--bars); stroke-width: 2; stroke-linecap: round; cursor: pointer; }
.notes .bar.unheard { stroke: #5c6478; }
.notes .bar.picked { stroke: var(--green); stroke-width: 3; }
.notes .hit { fill: transparent; cursor: pointer; outline: none; }
.notes .hit:focus-visible { fill: rgba(224, 224, 224, 0.15); }
.notes .axis { fill: var(--muted); font-size: 9px; font-family: var(--sans); }

.notes-caption {
  margin: 6px 0 16px;
  color: var(--muted);
  font-size: 13px;
}

.heard {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: 14px;
}
.heard output { font-variant-numeric: tabular-nums; font-weight: 600; margin-left: 4px; }
.heard input { width: 100%; }

.guess {
  display: block;
  width: 100%;
  max-width: 300px;
  margin: 10px auto 0;
  aspect-ratio: 1;
}
.guess .true { fill: rgba(99, 104, 110, 0.55); stroke: none; }
.guess .drawn { fill: none; stroke: var(--sand); stroke-width: 0.03; stroke-linejoin: round; }

.overlap {
  margin: 4px 0 8px;
  text-align: center;
  font-size: 15px;
}
.overlap span { font-size: 22px; font-weight: 600; font-variant-numeric: tabular-nums; }

.legend {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin: 0 0 12px;
  padding: 0;
  list-style: none;
  color: var(--muted);
  font-size: 12.5px;
}
.legend li { display: flex; align-items: center; gap: 6px; }
.sw { display: inline-block; width: 16px; height: 10px; border-radius: 2px; }
.sw-true { background: var(--true); }
.sw-guess { border: 2px solid var(--sand); height: 10px; }

.candidates {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}
.candidate { text-align: center; color: var(--muted); font-size: 11.5px; font-variant-numeric: tabular-nums; }
.candidate svg { display: block; width: 100%; aspect-ratio: 1; }
.candidate path { fill: none; stroke: var(--bars); stroke-width: 0.06; }
.candidate.top path { stroke: var(--sand); }

/* ---- the quiz ----------------------------------------------------------- */

.quiz {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr);
  gap: 20px 28px;
  padding: 48px 32px;
  border-top: 1px solid #333635;
  align-items: start;
}
.quiz-text p { color: #c9cbcf; font-family: var(--serif); font-size: 18px; line-height: 1.55; margin: 0 0 16px; max-width: 52ch; }
.quiz-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.action {
  padding: 9px 16px;
  border: 0;
  border-radius: 999px;
  background: var(--accent);
  color: var(--sand);
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
}
.action:hover { filter: brightness(1.12); }
.action.quiet { background: #2b2e2d; border: 1px solid #3b3e3d; }
.quiz-text .quiz-result { font-family: var(--sans); font-size: 15px; min-height: 1.5em; margin: 14px 0 6px; color: var(--sand); }
.quiz-score { display: flex; gap: 28px; margin: 0; }
.quiz-score div { display: flex; flex-direction: column-reverse; }
.quiz-score dt { color: var(--muted); font-size: 13px; }
.quiz-score dd { margin: 0; font-size: 22px; font-weight: 600; font-variant-numeric: tabular-nums; }

.quiz-choices { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.choice {
  position: relative;
  padding: 10px;
  border: 1px solid #3b3e3d;
  border-radius: 12px;
  background: #2b2e2d;
  cursor: pointer;
}
.choice svg { display: block; width: 100%; aspect-ratio: 1; }
.choice path { fill: rgba(71, 80, 92, 0.6); stroke: var(--bars); stroke-width: 0.04; stroke-linejoin: round; }
.choice:hover:not(:disabled) { border-color: var(--rim); }
.choice:disabled { cursor: default; }
.choice.right { border-color: var(--sand); background: var(--steel); }
.choice.right path { stroke: var(--sand); }
.choice.wrong { opacity: 0.55; }
.choice .tag {
  position: absolute;
  left: 8px;
  top: 8px;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--plate);
  color: var(--muted);
  font-size: 11.5px;
}
.choice .tag + .tag { top: 32px; }

/* ---- the isospectral pair ---------------------------------------------- */

.twins {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr);
  grid-template-areas: 'text stage' 'detail stage';
  gap: 12px 28px;
  padding: 48px 32px;
  border-top: 1px solid #333635;
}
.twins-text { grid-area: text; max-width: 52ch; }
.twins-text p { color: #c9cbcf; font-family: var(--serif); font-size: 18px; line-height: 1.55; margin: 0 0 12px; }
.twins-status { color: var(--muted) !important; font-family: var(--sans) !important; font-size: 14px !important; }
.twin-notes { margin-top: 14px; color: var(--muted); font-size: 14px; }
.twin-notes > div { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.twin-note {
  min-width: 40px;
  padding: 6px 10px;
  border: 1px solid #3b3e3d;
  border-radius: 8px;
  background: #2b2e2d;
  color: var(--sand);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
}
.twin-note:hover { border-color: var(--rim); }
.twin-note[aria-pressed='true'] { background: var(--accent); border-color: var(--accent); }

.twins-stage { grid-area: stage; min-height: 320px; height: 42vh; }
.twins-detail { grid-area: detail; display: flex; gap: 20px; align-items: flex-start; flex-wrap: wrap; }

.twins-table {
  border-collapse: collapse;
  font-size: 13px;
  font-variant-numeric: tabular-nums;
}
.twins-table caption { text-align: left; color: var(--muted); padding-bottom: 6px; }
.twins-table th, .twins-table td { padding: 3px 14px 3px 0; text-align: right; border-bottom: 1px solid #333635; }
.twins-table th { color: var(--muted); font-weight: 500; }
.twins-table th:first-child, .twins-table td:first-child { text-align: left; }

.twins-guess { margin: 0; width: 170px; }
.twins-guess svg { width: 100%; aspect-ratio: 1; display: block; }
.twins-guess path { fill: none; stroke: var(--sand); stroke-width: 0.035; }
.twins-guess figcaption { color: var(--muted); font-size: 12.5px; }

/* ---- essay -------------------------------------------------------------- */

.essay {
  max-width: 68ch;
  margin: 0 auto;
  padding: 56px 24px 96px;
  border-top: 1px solid #333635;
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.6;
  color: #c9cbcf;
}
.essay h3 { margin: 32px 0 6px; font-family: var(--sans); font-size: 15px; font-weight: 600; color: var(--sand); }
.essay a { color: var(--sand); text-underline-offset: 3px; }
.essay table { width: 100%; border-collapse: collapse; font-family: var(--sans); font-size: 14px; font-variant-numeric: tabular-nums; margin: 16px 0; }
.essay caption { text-align: left; color: var(--muted); padding-bottom: 8px; }
.essay th, .essay td { padding: 6px 10px 6px 0; text-align: left; border-bottom: 1px solid #3b3e3d; }
.essay td.num, .essay th.num { text-align: right; }

/* ---- small screens ------------------------------------------------------ */

@media (max-width: 960px) {
  .bench { grid-template-columns: 1fr; padding: 8px 16px 24px; }
  .stage { height: 56svh; min-height: 400px; }
  .masthead { padding: 20px 16px 4px; }
  .twins { grid-template-columns: 1fr; grid-template-areas: 'text' 'stage' 'detail'; padding: 36px 16px; }
  .quiz { grid-template-columns: 1fr; padding: 36px 16px; }
  .twins-stage { height: 30svh; min-height: 220px; }
}

@media (max-width: 560px) {
  .status { position: static; margin: 4px 0 6px; font-size: 13px; }
  .tray { gap: 10px; }
  .quiz-choices { grid-template-columns: repeat(2, 1fr); }
  .examples { flex-wrap: wrap; }
  .dial input { width: 90px; }
}