/* Colours follow the YTLab site (app/assets/stylesheets/application.css); the three panel
   colours: population red ochre, sample tin grey, distribution 1 dark blue, distribution 2 dark green
   (dark mode uses lighter tints of the same hues so they stay readable). */
:root {
  --bg: #faf8f4; --card: #ffffff; --ink: #1f1d1a; --muted: #6b665e;
  --line: #e4dfd6; --accent: #b4532a; --accent-soft: #f6e6dc; --ok: #2f7a4b;
  --on-accent: #ffffff;
  --pop: #a3402b; --pop-soft: #f6e2dc;
  --smp: #7b8187; --smp-soft: #eceef0;
  --d1: #2c4f87;  --d1-soft: #e1e8f3;
  --d2: #24603b;  --d2-soft: #e0eee5;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #181715; --card: #22201d; --ink: #ece8e1; --muted: #a29b90;
    --line: #36322d; --accent: #e08a5f; --accent-soft: #3a2a21; --ok: #6cc28f;
    --on-accent: #181715;
    --pop: #e27d62; --pop-soft: #3a2420;
    --smp: #a5abb1; --smp-soft: #2c2f32;
    --d1: #7fa8e6;  --d1-soft: #1f2a3a;
    --d2: #6cc28f;  --d2-soft: #1f3327;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #181715; --card: #22201d; --ink: #ece8e1; --muted: #a29b90;
  --line: #36322d; --accent: #e08a5f; --accent-soft: #3a2a21; --ok: #6cc28f;
  --on-accent: #181715;
  --pop: #e27d62; --pop-soft: #3a2420;
  --smp: #a5abb1; --smp-soft: #2c2f32;
  --d1: #7fa8e6;  --d1-soft: #1f2a3a;
  --d2: #6cc28f;  --d2-soft: #1f3327;
  color-scheme: dark;
}

* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Noto Sans TC", "Helvetica Neue", sans-serif;
  font-size: 15px; line-height: 1.5;
  -webkit-text-size-adjust: 100%;
}
a { color: var(--accent); }

.wrap {
  max-width: 1180px; margin: 0 auto;
  padding: 20px max(16px, env(safe-area-inset-right, 0px)) 48px max(16px, env(safe-area-inset-left, 0px));
}

/* Header */
.top { display: flex; align-items: center; gap: 14px; }
.logo img { display: block; width: 48px; height: 48px; border-radius: 10px; }
.titles { min-width: 0; }
h1 { font-size: clamp(19px, 3vw, 26px); line-height: 1.2; margin: 0; text-wrap: balance; }
.sub { margin: 2px 0 0; color: var(--muted); font-size: 14px; }
.links { margin-left: auto; font-size: 14px; white-space: nowrap; }
.links a { text-decoration: none; border: 1px solid var(--line); border-radius: 999px; padding: 5px 12px; background: var(--card); }
.links a:hover { border-color: var(--accent); }

/* Comparison presets */
.presets { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-top: 16px; }
button.chip { min-height: 32px; padding: 4px 12px; border-radius: 999px; font-size: 13.5px; }
button.chip[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.preset-tip {
  margin: 10px 0 0; padding: 8px 12px; font-size: 14px; max-width: 900px;
  border-left: 3px solid var(--accent); background: var(--card); border-radius: 0 8px 8px 0;
}

/* Toolbar */
.toolbar {
  position: sticky; top: 0; z-index: 10;
  display: flex; flex-wrap: wrap; align-items: center; gap: 8px;
  margin: 8px 0 12px; padding: 10px 0;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  -webkit-backdrop-filter: blur(6px); backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}
.tb-label { color: var(--muted); font-size: 13px; margin-right: 2px; }
.spacer { flex: 1; }
button {
  font: inherit; font-size: 14px; min-height: 36px; padding: 6px 14px;
  border-radius: 8px; border: 1px solid var(--line);
  background: var(--card); color: var(--ink); cursor: pointer;
  font-variant-numeric: tabular-nums;
}
button:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
button.primary { background: var(--accent); border-color: var(--accent); color: var(--on-accent); font-weight: 600; }
button.primary:hover:not(:disabled) { color: var(--on-accent); filter: brightness(1.08); }
button.ghost { background: transparent; }
button:disabled, select:disabled { opacity: .5; cursor: default; }
button:focus-visible, select:focus-visible, input:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* Panels */
.panels { position: relative; display: grid; gap: 12px; }
.panel {
  --panel: var(--pop); --panel-soft: var(--pop-soft);
  display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 16px;
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  box-shadow: inset 4px 0 0 var(--panel);
  padding: 14px 16px 14px 20px;
}
#p-sample { --panel: var(--smp); --panel-soft: var(--smp-soft); }
#p-draws { --panel: var(--smp); --panel-soft: var(--smp-soft); }
#p-mean { --panel: var(--d1); --panel-soft: var(--d1-soft); }
#p-check { --panel: var(--d2); --panel-soft: var(--d2-soft); }
.panel[data-dist="0"] { --panel: var(--d1); --panel-soft: var(--d1-soft); }
.panel[data-dist="1"] { --panel: var(--d2); --panel-soft: var(--d2-soft); }
.panel h2 { font-size: 15px; margin: 0 0 6px; display: flex; flex-wrap: wrap; align-items: center; gap: 2px 8px; }
.panel h2 .cap { color: var(--panel); font-weight: 600; }
.step {
  display: inline-grid; place-items: center; width: 22px; height: 22px; border-radius: 50%;
  background: var(--panel-soft); color: var(--panel); font-size: 12px; font-weight: 700;
}
.side { min-width: 0; }
.side label { display: block; font-size: 12px; color: var(--muted); margin: 6px 0 3px; }
select {
  width: 100%; font: inherit; font-size: 14px; padding: 6px 8px; min-height: 34px;
  border-radius: 8px; border: 1px solid var(--line); background: var(--card); color: var(--ink);
}
.pair { display: grid; grid-template-columns: minmax(0, 1fr) 76px; gap: 8px; }
.checks { display: flex; gap: 16px; margin-top: 10px; }
.checks label { display: flex; align-items: center; gap: 6px; margin: 0; font-size: 13px; color: var(--ink); cursor: pointer; }
.checks input { accent-color: var(--panel); margin: 0; }
.hint, .note { margin: 10px 0 0; font-size: 12.5px; color: var(--muted); }
.note { margin-top: 0; }

.readout { display: grid; grid-template-columns: 1fr 1fr; gap: 3px 14px; margin: 10px 0 0; font-size: 13px; }
.readout div { display: flex; justify-content: space-between; gap: 6px; border-bottom: 1px dotted var(--line); padding-bottom: 1px; min-width: 0; }
.readout dt { color: var(--muted); white-space: nowrap; }
.readout dd { margin: 0; font-variant-numeric: tabular-nums; white-space: nowrap; }
.readout .head { grid-column: 1 / -1; border: 0; margin-top: 4px; font-size: 11.5px; letter-spacing: .04em; text-transform: uppercase; color: var(--muted); }
.readout .theory dd { font-weight: 600; }

.plot { min-width: 0; display: flex; align-items: stretch; }
.plot canvas { display: block; width: 100%; height: 100%; min-height: 120px; }
#c-pop { height: 190px; touch-action: none; cursor: crosshair; }
#c-sample { height: 140px; min-height: 140px; }
.dist canvas { height: 240px; min-height: 220px; }
.series canvas { height: 250px; min-height: 220px; }
#c-draws { height: 150px; min-height: 150px; }
.ncount { font-size: 13px; color: var(--muted); font-variant-numeric: tabular-nums; margin-left: 4px; }
button.play[aria-pressed="true"] { background: var(--ink); border-color: var(--ink); color: var(--bg); }
input[type="range"] { width: 100%; accent-color: var(--panel); margin: 8px 0 0; }
.side label output { color: var(--ink); font-variant-numeric: tabular-nums; margin-left: 4px; }

#overlay { position: absolute; inset: 0; width: 100%; height: 100%; pointer-events: none; z-index: 5; }

/* About */
.about { margin-top: 16px; background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px; }
.about summary { cursor: pointer; font-weight: 600; }
.about-body { max-width: 760px; color: var(--ink); }
.about-body p, .about-body li { font-size: 14px; }
.about-body ul { padding-left: 20px; }

footer { margin-top: 20px; color: var(--muted); font-size: 12.5px; }

@media (max-width: 760px) {
  .panel { grid-template-columns: minmax(0, 1fr); gap: 8px; }
  .dist canvas { height: 220px; }
  .sub { font-size: 13px; }
  .tb-label { display: none; }
  button { padding: 6px 11px; }
}