/* The common look of the BrainFlux demos.  Plain CSS: custom properties for the colours (light
   and dark follow the system setting), a header bar, panels, compact controls and the
   experiments drawer. */

:root {
  --bg: #f4f3ef;
  --panel: #ffffff;
  --panel-2: #f0efea;
  --ink: #1d1d1f;
  --ink-2: #55565c;
  --ink-3: #8a8b91;
  --line: #d9d8d2;
  --accent: #2f62d8;
  --accent-ink: #ffffff;
  --accent-soft: #e3eafb;
  --warn: #b3261e;
  --good: #1f7a3a;
  --canvas-bg: #000000;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.06), 0 2px 8px rgba(0, 0, 0, 0.05);
  --radius: 8px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131417;
    --panel: #1c1d22;
    --panel-2: #24252b;
    --ink: #ececef;
    --ink-2: #b4b5bc;
    --ink-3: #7d7e86;
    --line: #34353d;
    --accent: #7aa2ff;
    --accent-ink: #0d1220;
    --accent-soft: #233056;
    --warn: #ff8a80;
    --good: #7ad694;
    --shadow: none;
  }
}

* { box-sizing: border-box; }
/* The hidden attribute must win over any display: set below. */
[hidden] { display: none !important; }

html, body { margin: 0; background: var(--bg); color: var(--ink); }
body { font: 14px/1.45 var(--font); -webkit-text-size-adjust: 100%; }

a { color: var(--accent); }

/* ------------------------------------------------------------------ header */

.bar {
  display: flex; align-items: center; gap: 12px;
  padding: 8px 16px; border-bottom: 1px solid var(--line); background: var(--panel);
  position: sticky; top: 0; z-index: 20;
}
.bar .home { font-weight: 700; text-decoration: none; color: var(--ink); letter-spacing: 0.02em; }
.bar .home span { color: var(--accent); }
.bar h1 { font-size: 16px; font-weight: 600; margin: 0; color: var(--ink-2); }
.bar .spacer { flex: 1; }

/* ----------------------------------------------------------------- controls */

button, select, input, textarea { font: inherit; color: inherit; }

button {
  background: var(--panel); border: 1px solid var(--line); border-radius: 6px;
  padding: 4px 10px; cursor: pointer; min-height: 30px; line-height: 1.2;
}
button:hover { border-color: var(--ink-3); }
button:focus-visible, select:focus-visible, input:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
button.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 600; }
button[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); color: var(--ink); }
button:disabled { opacity: 0.45; cursor: default; }
button.icon { padding: 3px; min-width: 32px; display: inline-flex; align-items: center; justify-content: center; }
button.icon svg { width: 20px; height: 20px; }

select {
  background: var(--panel); border: 1px solid var(--line); border-radius: 6px;
  padding: 4px 6px; min-height: 30px;
}

input[type="text"], input[type="number"], textarea {
  background: var(--panel); border: 1px solid var(--line); border-radius: 6px; padding: 4px 6px;
}
input[type="number"] { width: 6em; -moz-appearance: textfield; appearance: textfield; }
input[type="number"]::-webkit-inner-spin-button, input[type="number"]::-webkit-outer-spin-button { -webkit-appearance: none; margin: 0; }
input.bad, textarea.bad { border-color: var(--warn); }

.seg { display: inline-flex; flex-wrap: wrap; }
.seg > button { border-radius: 0; margin-left: -1px; }
.seg > button:first-child { border-radius: 6px 0 0 6px; margin-left: 0; }
.seg > button:last-child { border-radius: 0 6px 6px 0; }
.seg > button[aria-pressed="true"] { position: relative; z-index: 1; }

/* A slider with its label and an editable value. */
.slider { display: grid; grid-template-columns: minmax(3.2em, auto) 1fr 5.2em; align-items: center; gap: 6px; }
.slider label { color: var(--ink-2); white-space: nowrap; }
.slider label math { font-size: 1.05em; }
.slider input[type="range"] { width: 100%; min-width: 60px; accent-color: var(--accent); }
.slider input[type="number"] { width: 100%; padding: 2px 4px; text-align: right; }

.row { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.stack { display: flex; flex-direction: column; gap: 8px; }
.label { color: var(--ink-2); font-size: 12px; text-transform: uppercase; letter-spacing: 0.05em; }
.muted { color: var(--ink-3); }
.small { font-size: 12px; }
.mono { font-family: var(--mono); font-variant-numeric: tabular-nums; }
/* A live number in a readout: a fixed width (set where it is made, in ch), right-aligned, tabular
   figures, so that it and what follows it keep their places as it changes (ui.js: numSlot). */
.fixnum { display: inline-block; text-align: right; white-space: pre; font-variant-numeric: tabular-nums; }
/* A number kept on one line with the words touching it (setSlots). */
.nobr { white-space: nowrap; }

.panel {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 10px;
}

/* A typed expression with its MathML preview and error line. */
.expr { display: grid; gap: 4px; }
.expr .line { display: flex; gap: 6px; align-items: center; }
.expr .line > label { color: var(--ink-2); white-space: nowrap; }
.expr input { flex: 1; min-width: 0; font-family: var(--mono); }
.expr .preview { min-height: 1.6em; overflow-x: auto; color: var(--ink); }
.expr .preview math { font-size: 1.15em; }
.expr .error { color: var(--warn); font-size: 12px; min-height: 0; }
.params { display: grid; gap: 4px; }

/* -------------------------------------------------------------- the drawer */

.drawer {
  position: fixed; top: 0; right: 0; bottom: 0; width: min(440px, 100vw);
  background: var(--panel); border-left: 1px solid var(--line); z-index: 30;
  transform: translateX(100%); transition: transform 0.2s ease; overflow-y: auto;
  padding: 0 18px 40px; box-shadow: -4px 0 24px rgba(0, 0, 0, 0.12);
}
.drawer.open { transform: none; }
.drawer header {
  position: sticky; top: 0; background: var(--panel); display: flex; align-items: center;
  gap: 8px; padding: 12px 0 8px; border-bottom: 1px solid var(--line); margin-bottom: 8px;
}
.drawer header h2 { margin: 0; font-size: 17px; flex: 1; }
.drawer h3 { font-size: 15px; margin: 18px 0 4px; }
.drawer p, .drawer li { color: var(--ink); }
.drawer .exp { border-top: 1px solid var(--line); padding-top: 4px; }
.drawer .exp .setup { margin: 4px 0 2px; }
.drawer math[display="block"] { margin: 8px 0; }
.drawer figure { margin: 8px 0; }
.drawer figure img { max-width: 100%; border-radius: 4px; }
/* The still picture of an experiment (tools/frames.py), under its "Set it up" button. */
.drawer figure.frame { margin: 6px 0 8px; }
.drawer figure.frame img { display: block; width: 100%; height: auto; border: 1px solid var(--line); border-radius: 6px; cursor: pointer; background: var(--panel-2); }
.drawer figure.frame img:hover { border-color: var(--accent); }
/* "Start here": the first thing in the drawer, in plain words: what the page shows, what to
   drag or click, what to look for.  The theory goes at the end of the drawer, under "How it
   works". */
.drawer .start {
  background: var(--panel-2); border: 1px solid var(--line); border-radius: 8px;
  padding: 10px 14px; margin: 10px 0 14px;
}
.drawer .start h3 { margin: 0 0 6px; font-size: 14px; text-transform: uppercase; letter-spacing: 0.04em; color: var(--ink-2); }
.drawer .start p { margin: 6px 0; }
.drawer .start p:last-child { margin-bottom: 0; }
.drawer .start kbd, .drawer .start b { font-weight: 600; }
@media (prefers-reduced-motion: reduce) { .drawer { transition: none; } }

/* ------------------------------------------------------------------- misc */

canvas { display: block; touch-action: none; }
/* A one-line hint on or under the main picture: what to drag or click, visible on opening. */
.hint { font-size: 13px; color: var(--ink-2); }
.hint::before { content: "\2192\00a0"; color: var(--accent); }
.pixelated { image-rendering: pixelated; image-rendering: crisp-edges; }
kbd { font-family: var(--mono); font-size: 0.9em; border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 4px; padding: 0 4px; background: var(--panel-2); }
.toast {
  position: fixed; left: 50%; bottom: 20px; transform: translateX(-50%); z-index: 40;
  background: var(--ink); color: var(--bg); padding: 8px 14px; border-radius: 8px;
  opacity: 0; transition: opacity 0.2s; pointer-events: none; max-width: 90vw;
}
.toast.show { opacity: 0.94; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }