/* Boids. Colors are tokens (light/dark); the canvas reads the --sky, --bird… tokens too. */
:root {
  --bg: #f2f5f9;
  --panel: #ffffff;
  --line: #d8dee8;
  --text: #17202f;
  --muted: #5a6577;
  --accent: #2563c9;
  --btn: #edf1f6;
  --btn-on: #dbe6fa;
  --shadow: 0 1px 3px rgba(20, 30, 60, 0.06);
  /* canvas */
  --sky: #e6eef7;
  --sky-edge: #d3dfec;
  --bird: #263248;
  --focus: #e8590c;
  --nb: #1c7ed6;
  --view: rgba(28, 126, 214, 0.13);
  --rock: #9aa5b8;
  --rock-edge: #7b8699;
  --sep: #d6336c;
  --ali: #1864ab;
  --coh: #2b8a3e;
  --pointer: rgba(232, 89, 12, 0.5);
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0b1020; --panel: #131a2e; --line: #26304a; --text: #dfe5f2; --muted: #8e99b2; --accent: #7fa6ff;
    --btn: #1b2340; --btn-on: #283766; --shadow: none;
    --sky: #0f1628; --sky-edge: #1d2742; --bird: #c7d3ee; --focus: #ffa94d; --nb: #4dabf7; --view: rgba(77, 171, 247, 0.14);
    --rock: #3a4562; --rock-edge: #55617f; --sep: #ff6b9a; --ali: #74c0fc; --coh: #69db7c; --pointer: rgba(255, 169, 77, 0.5);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0b1020; --panel: #131a2e; --line: #26304a; --text: #dfe5f2; --muted: #8e99b2; --accent: #7fa6ff;
  --btn: #1b2340; --btn-on: #283766; --shadow: none;
  --sky: #0f1628; --sky-edge: #1d2742; --bird: #c7d3ee; --focus: #ffa94d; --nb: #4dabf7; --view: rgba(77, 171, 247, 0.14);
  --rock: #3a4562; --rock-edge: #55617f; --sep: #ff6b9a; --ali: #74c0fc; --coh: #69db7c; --pointer: rgba(255, 169, 77, 0.5);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.45 system-ui, sans-serif;
}

.top {
  display: flex; align-items: center; gap: 8px;
  max-width: 1400px; margin: 0 auto; padding: 10px 16px 6px;
}
h1 { font-size: 20px; margin: 0; flex: 1; min-width: 0; }
h1 .sub { font-size: 14px; font-weight: 400; color: var(--muted); margin-left: 4px; }
h2 { font-size: 16px; margin: 0 0 8px; }
h3 { font-size: 15px; margin: 12px 0 6px; }
.hub-link { color: var(--muted); font-size: 13px; text-decoration: none; white-space: nowrap; }
.hub-link:hover { color: var(--text); text-decoration: underline; }
/* "All projects" only on the hosted site (where ../ is the homepage), not from disk or in the app */
html.hosted:not(.installed) .hub-link[hidden] { display: inline; }
.muted { color: var(--muted); }

/* stage: the canvas, full width */
.stage { max-width: 1400px; margin: 0 auto; padding: 0 16px; }
.canvas-wrap {
  position: relative;
  height: clamp(300px, 64vh, 760px);
  border: 1px solid var(--sky-edge); border-radius: 12px; overflow: hidden;
  background: var(--sky);
}
#sky { display: block; width: 100%; height: 100%; touch-action: pan-y; cursor: crosshair; user-select: none; -webkit-user-select: none; -webkit-tap-highlight-color: transparent; }
.debug, .paused-note {
  position: absolute; margin: 0; pointer-events: none;
  font: 12px/1.3 ui-monospace, monospace; color: var(--muted);
  background: var(--panel); border: 1px solid var(--line); border-radius: 6px; padding: 2px 6px; opacity: 0.9;
}
.debug { left: 8px; top: 8px; }
.paused-note { right: 8px; top: 8px; font: 600 12px/1.3 system-ui, sans-serif; }

.toolbar { display: flex; flex-wrap: wrap; gap: 8px 14px; align-items: center; margin-top: 8px; }
.group { display: flex; align-items: center; gap: 4px; flex-wrap: wrap; }
.group .label { font-size: 13px; color: var(--muted); margin-right: 2px; }
.seg button[aria-checked="true"], #play[aria-pressed="true"] { background: var(--btn-on); border-color: var(--accent); font-weight: 600; }

button {
  font: inherit; font-size: 14px; color: var(--text); background: var(--btn);
  border: 1px solid var(--line); border-radius: 6px; padding: 6px 11px; cursor: pointer;
}
button:hover { border-color: var(--accent); }
button:disabled { opacity: 0.45; cursor: default; border-color: var(--line); }
button.primary { background: var(--accent); border-color: var(--accent); color: var(--panel); font-weight: 600; }
button:focus-visible, input:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
#play { min-width: 4.6em; }

.legend[hidden] { display: none; }
.legend { display: flex; flex-wrap: wrap; gap: 4px 14px; margin-top: 8px; font-size: 13px; color: var(--muted); align-items: center; }
.legend span { display: inline-flex; align-items: center; gap: 5px; }
.legend .hint { font-style: italic; }
.sw { display: inline-block; width: 12px; height: 12px; border-radius: 50%; flex: none; }
.sw.focus { background: var(--focus); }
.sw.view { background: var(--view); border: 1px solid var(--nb); border-radius: 3px; }
.sw.nb { background: var(--nb); }
.sw.arrow { width: 16px; height: 3px; border-radius: 2px; }
.sw.sep { background: var(--sep); }
.sw.ali { background: var(--ali); }
.sw.coh { background: var(--coh); }
.c-sep { color: var(--sep); }
.c-ali { color: var(--ali); }
.c-coh { color: var(--coh); }

/* panels */
.panels {
  display: grid; gap: 14px; align-items: start;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  max-width: 1400px; margin: 0 auto; padding: 14px 16px 32px;
}
.card {
  background: var(--panel); border: 1px solid var(--line); border-radius: 12px;
  padding: 12px 14px; min-width: 0; box-shadow: var(--shadow);
}
.about p { font-size: 13.5px; color: var(--muted); margin: 6px 0; }

label { display: flex; flex-direction: column; gap: 2px; font-size: 13px; color: var(--muted); min-width: 0; }
label.slider { margin: 6px 0; }
label.slider output { position: absolute; right: 0; top: 0; color: var(--text); font-variant-numeric: tabular-nums; }
label.slider { position: relative; }
input[type="range"] { width: 100%; margin: 2px 0; accent-color: var(--accent); }
input[type="checkbox"] { width: 1.05rem; height: 1.05rem; margin: 0; accent-color: var(--accent); }
label.check { flex-direction: row; align-items: center; gap: 7px; font-size: 14.5px; color: var(--text); cursor: pointer; }
.rule { padding: 8px 0; border-top: 1px solid var(--line); }
.rule:first-of-type { border-top: 0; padding-top: 0; }
.view-toggle { border-top: 1px solid var(--line); padding-top: 10px; margin-top: 2px; }

.presets { display: flex; flex-wrap: wrap; gap: 6px; }
.presets button[aria-pressed="true"] { background: var(--btn-on); border-color: var(--accent); }
#pwa-install { margin-top: 12px; width: 100%; }

/* lesson stepper */
.lesson h3 { margin: 0 0 6px; }
.lesson p { margin: 6px 0; font-size: 14.5px; }
.lesson p.muted { font-size: 13.5px; }
#lesson { min-height: 11.5em; }
.lesson-nav { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin-top: 10px; }
.dots { display: flex; gap: 5px; }
.dots i { width: 7px; height: 7px; border-radius: 50%; background: var(--line); }
.dots i.on { background: var(--accent); }

.pwa-toast {
  position: fixed; left: 50%; bottom: 1rem; transform: translateX(-50%); z-index: 60;
  display: flex; gap: .8rem; align-items: center; max-width: calc(100% - 2rem);
  padding: .6rem .7rem .6rem 1rem; border-radius: 12px;
  background: var(--panel); color: var(--text); border: 1px solid var(--line); box-shadow: 0 6px 24px rgba(0, 0, 0, .18);
}

@media (max-width: 600px) {
  h1 .sub { display: none; }
  .canvas-wrap { height: clamp(280px, 58vh, 560px); }
  .toolbar { gap: 8px 10px; }
  button { padding: 6px 9px; }
}