:root {
  --bg: #0a0c14;
  --panel: #131725;
  --panel-2: #1a2033;
  --line: #262e45;
  --text: #e6e9f2;
  --muted: #8b93ad;
  --accent: #4fd1c5;
  --accent-2: #a78bfa;
  --hot: #f6ad55;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: radial-gradient(1200px 700px at 50% -10%, #17203a 0%, var(--bg) 60%);
  color: var(--text);
  font: 15px/1.55 ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  min-height: 100%;
}

.wrap {
  max-width: 880px;
  margin: 0 auto;
  padding: 40px 20px 60px;
}

header { text-align: center; margin-bottom: 28px; }

h1 {
  margin: 0 0 10px;
  font-size: clamp(30px, 6vw, 46px);
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(100deg, var(--accent), var(--accent-2) 60%, var(--hot));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.tagline {
  margin: 0 auto;
  max-width: 620px;
  color: var(--muted);
}

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 20px;
  margin-bottom: 16px;
}

/* transport */

.transport {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.btn {
  font: inherit;
  font-weight: 600;
  color: var(--text);
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 11px 18px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  transition: transform .08s ease, border-color .15s ease, background .15s ease;
}

.btn:hover { border-color: #3d4763; }
.btn:active { transform: translateY(1px); }

.btn.primary {
  background: linear-gradient(140deg, #14b8a6, #0d9488);
  border-color: #2dd4bf;
  color: #04211f;
}

.transport-btns { display: flex; gap: 8px; }

.btn .icon { font-size: 11px; line-height: 1; }

/* while the excitation is sounding, play reads as engaged */
.btn.primary[aria-pressed="true"] {
  background: linear-gradient(140deg, #2dd4bf, #14b8a6);
  box-shadow: 0 0 0 3px rgba(45, 212, 191, .18);
}

.btn kbd {
  font: 11px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
  opacity: .65;
  border: 1px solid currentColor;
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 2px 5px;
  margin-left: 2px;
}

.excitation {
  flex: 1 1 220px;
  min-width: 180px;
  max-width: 340px;
}

.excitation label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 4px;
}

.excitation .rate {
  text-transform: none;
  letter-spacing: 0;
  font-weight: 500;
  color: var(--hot);
  margin-left: 8px;
  font-variant-numeric: tabular-nums;
}

#excite::-webkit-slider-thumb { border-color: var(--hot); }
#excite::-moz-range-thumb { border-color: var(--hot); }

/* the min-width also has to clear the longest dimension label, or sliding onto a
   fractional value would widen the row and bump the readouts onto a second line */
.readout {
  margin-left: auto;
  text-align: right;
  min-width: 120px;
}

.readout + .readout { margin-left: 0; }

.readout .big {
  font-size: 25px;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}

.readout .sub {
  color: var(--muted);
  font-size: 12.5px;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

/* controls */

.control { margin-bottom: 20px; }
.control:last-child { margin-bottom: 0; }

.control label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 9px;
}

.hint {
  text-transform: none;
  letter-spacing: 0;
  font-weight: 500;
  color: var(--accent);
  opacity: 0;
  transition: opacity .15s ease;
  margin-left: 8px;
}

.hint.on { opacity: 1; }

input[type=range] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 26px;
  /* browsers default range inputs to a 2px margin; zeroing it lets the tick marks
     below be placed from the element's own width */
  margin: 0;
  background: transparent;
  cursor: pointer;
}

input[type=range]::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 3px;
  background: #2b3350;
}

input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px; height: 20px;
  margin-top: -7px;
  border-radius: 50%;
  background: var(--text);
  border: 3px solid var(--accent);
  box-shadow: 0 2px 8px rgba(0,0,0,.5);
}

input[type=range]::-moz-range-track {
  height: 6px;
  border-radius: 3px;
  background: #2b3350;
}

input[type=range]::-moz-range-thumb {
  width: 20px; height: 20px;
  border-radius: 50%;
  background: var(--text);
  border: 3px solid var(--accent);
}

#dim::-webkit-slider-thumb { border-color: var(--accent-2); }
#dim::-moz-range-thumb { border-color: var(--accent-2); }

.scale {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: #5f6884;
  font-variant-numeric: tabular-nums;
  padding: 0 8px;
}

.scale.ticks span { flex: 1; text-align: center; }
.scale.ticks span:first-child { text-align: left; }
.scale.ticks span:last-child { text-align: right; }

/* labels pinned to exact slider values, each with a tick mark on the track */
.scale.marks {
  display: block;
  position: relative;
  height: 26px;
  padding: 0;
}

.scale.marks span {
  position: absolute;
  top: 9px;
  transform: translateX(-50%);
  white-space: nowrap;
}

.scale.marks span::before {
  content: "";
  position: absolute;
  left: 50%;
  top: -9px;
  width: 1px;
  height: 7px;
  background: #3d4763;
}

.scale.marks b { font-weight: 600; }
.scale.marks i { font-style: normal; margin-left: 4px; }
.scale.marks span.on { color: var(--accent-2); }
.scale.marks span.on::before { background: var(--accent-2); }

.segmented {
  display: inline-flex;
  gap: 4px;
  padding: 4px;
  background: #0e1220;
  border: 1px solid var(--line);
  border-radius: 11px;
}

.segmented button {
  font: inherit;
  font-size: 13.5px;
  font-weight: 600;
  color: var(--muted);
  background: transparent;
  border: 1px solid transparent;
  border-radius: 8px;
  padding: 7px 15px;
  cursor: pointer;
}

.segmented button em {
  font-style: normal;
  font-weight: 400;
  font-size: 12px;
  opacity: .7;
  margin-left: 6px;
}

.segmented button.on {
  color: var(--text);
  background: var(--panel-2);
  border-color: var(--accent-2);
}

.control-row { display: flex; gap: 22px; }
.control-row .control { flex: 1; margin-bottom: 0; }

/* presets */

.presets {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.presets-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--muted);
  margin-right: 4px;
}

.chip {
  font: inherit;
  font-size: 12.5px;
  color: var(--text);
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 6px 12px;
  cursor: pointer;
}

.chip em {
  font-style: normal;
  color: var(--accent-2);
  font-variant-numeric: tabular-nums;
  margin-left: 5px;
}

.chip:hover { border-color: #3d4763; }
.chip.active { border-color: var(--accent-2); background: #241f3d; }

/* viz */

.viz-head h2 {
  margin: 0 0 4px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--muted);
}

.viz-head p {
  margin: 0 0 14px;
  font-size: 13px;
  color: #737c98;
  max-width: 660px;
}

canvas {
  display: block;
  width: 100%;
  border-radius: 8px;
  background: #0b0e18;
  border: 1px solid var(--line);
}

#spectrum { height: 260px; }
#wave { height: 150px; }

.ratios {
  margin-top: 12px;
  font-size: 12.5px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

#ratioList { color: var(--accent); }

/* explanation */

.explain summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--accent);
  list-style: none;
}

.explain summary::before {
  content: "+ ";
  font-weight: 700;
}

.explain[open] summary::before { content: "\2212  "; }
.explain[open] summary { margin-bottom: 12px; }

.explain p {
  color: #a8b0c8;
  font-size: 14px;
}

.explain h3 {
  margin: 22px 0 8px;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--accent-2);
}

.explain em { color: var(--text); font-style: normal; }

.eq {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  color: var(--accent) !important;
  background: #0d1120;
  border-left: 2px solid var(--accent-2);
  padding: 9px 12px;
  border-radius: 4px;
  overflow-x: auto;
}

.eq.inline {
  display: inline;
  padding: 1px 5px;
  border-left: none;
  border-radius: 3px;
  white-space: nowrap;
}

.caveat {
  border-top: 1px solid var(--line);
  padding-top: 12px;
  font-size: 13px !important;
  color: #6f7794 !important;
}

footer {
  text-align: center;
  color: #5f6884;
  font-size: 12.5px;
  margin-top: 26px;
}

@media (max-width: 640px) {
  /* five names do not fit across a narrow track; the readout still spells them out */
  .scale.marks i { display: none; }
}

@media (max-width: 560px) {
  .transport { justify-content: space-between; }
  .readout { margin-left: 0; }
  .control-row { flex-direction: column; gap: 18px; }
}