/* ============================================================
   ml-lab · the *-lab series — EDITORIAL / ACADEMIC theme.
   Warm paper, Fraunces serif display, layered depth, one
   per-course accent (kept in --accent). Course & project pages
   inherit this via :root tokens, so this file re-skins all three.

   To re-skin another *-lab course: change --accent ONLY.
   ============================================================ */
:root {
  --bg:        #faf6ee;   /* warm cream page          */
  --paper:     #fffdf8;   /* cards / raised surfaces  */
  --ink:       #221d16;   /* primary text             */
  --ink-soft:  #544b3d;   /* secondary prose          */
  --muted:     #8c8273;   /* captions, meta           */
  --rule:      #e9e0cf;   /* hairline borders         */
  --rule-h:    #d8ccb4;   /* stronger borders         */

  --accent:      #0284c7;                                        /* per-course colour */
  --accent-soft: color-mix(in srgb, var(--accent) 12%, transparent);
  --accent-deep: color-mix(in srgb, var(--accent) 70%, #15120e);
  --gold:        #b45309;                                        /* shared 2nd accent */

  --good: #16A34A;  --warn: #F59E0B;  --bad: #DC2626;

  --shadow-sm: 0 1px 2px rgba(34,29,22,.06);
  --shadow:    0 2px 4px rgba(34,29,22,.05), 0 14px 30px -18px rgba(34,29,22,.28);

  --font-display: 'Fraunces', Georgia, 'Times New Roman', serif;
  --font-sans:    'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono:    'JetBrains Mono', ui-monospace, Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
html, body { margin: 0; padding: 0; color: var(--ink); font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; }
body {
  font-size: 15.5px; line-height: 1.6;
  background:
    radial-gradient(1100px 560px at 100% -10%, #fff8ea 0%, rgba(255,248,234,0) 55%),
    radial-gradient(820px 460px at -8% 0%, #f5eede 0%, rgba(245,238,222,0) 50%),
    var(--bg);
}

a { color: var(--accent); text-decoration: none; border-bottom: 1px solid transparent;
  transition: color 120ms, border-color 120ms; }
a:hover { color: var(--accent-deep); border-bottom-color: currentColor; }
::selection { background: var(--accent-soft); }

/* HEADER ---------------------------------------------------- */
header {
  position: sticky; top: 0; z-index: 30;
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: 0.85rem 1.6rem;
  background: rgba(250,246,238,0.86);
  backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid var(--rule);
}
.title { display: flex; align-items: baseline; gap: 0.6rem; font-size: 0.95rem; }
.title .dot { width: 11px; height: 11px; border-radius: 999px; align-self: center;
  background: conic-gradient(from 140deg, var(--accent), var(--gold), var(--accent));
  box-shadow: 0 0 0 3px var(--accent-soft); }
.title strong { font-family: var(--font-display); font-weight: 600; font-size: 1.18rem;
  letter-spacing: -0.01em; color: var(--ink); }
.title .sub { color: var(--muted); font-size: 0.76rem; font-family: var(--font-sans);
  text-transform: uppercase; letter-spacing: 0.1em; }
nav { display: flex; gap: 0.7rem; flex-wrap: wrap; }
nav a {
  color: var(--ink-soft); font-size: 0.78rem; font-weight: 500;
  padding: 0.2em 0.5em; border-radius: 6px; border-bottom: 0;
}
nav a:hover { color: var(--accent-deep); background: var(--accent-soft); }

main { max-width: 1080px; margin: 0 auto; padding: 1.6rem; display: flex;
  flex-direction: column; gap: 1.3rem; }

/* DEMO / SECTION CARD --------------------------------------- */
.demo {
  position: relative; background: var(--paper);
  border: 1px solid var(--rule); border-radius: 14px;
  padding: 1.15rem 1.4rem 1.4rem;
  box-shadow: var(--shadow-sm); transition: box-shadow .2s, transform .2s;
}
.demo:hover { box-shadow: var(--shadow); }
.demo::before { content: ''; position: absolute; left: 0; top: 20px; bottom: 20px; width: 3px;
  border-radius: 3px; background: linear-gradient(var(--accent), var(--gold)); opacity: 0;
  transition: opacity .2s; }
.demo:hover::before { opacity: .85; }
.demo h2 {
  font-family: var(--font-display); font-weight: 600; font-size: 1.32rem;
  letter-spacing: -0.01em; margin: 0 0 0.35rem; color: var(--ink); line-height: 1.18;
}
.demo h2::before {
  content: ''; display: inline-block;
  width: 9px; height: 9px; border-radius: 3px;
  background: var(--accent); margin-right: 0.55em; transform: translateY(-2px);
}
.cap { color: var(--ink-soft); font-size: 0.9rem; margin: 0 0 1rem; max-width: 74ch; }

.row {
  display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(230px, 1fr);
  gap: 1.2rem;
}
@media (max-width: 760px) { .row { grid-template-columns: 1fr; } }

.canvas-wrap {
  background: #fff; border: 1px solid var(--rule); border-radius: 9px;
  overflow: hidden; box-shadow: var(--shadow-sm);
}
canvas { display: block; width: 100%; height: auto; }

.ctrls { display: flex; flex-direction: column; gap: 0.7rem; font-size: 0.85rem; }
.ctrls label { display: flex; flex-direction: column; gap: 0.28rem; color: var(--ink-soft);
  font-weight: 500; }
.ctrls label .mono { color: var(--ink); font-weight: 600; font-size: 0.86rem; }
.ctrls label.check { flex-direction: row; align-items: center; gap: 0.4em; cursor: pointer; }

select, input[type=range], input[type=text], button.btn { font-family: inherit; font-size: 0.86rem; }
select, input[type=text] {
  padding: 0.45em 0.65em; border: 1px solid var(--rule-h); border-radius: 7px;
  background: var(--paper); color: var(--ink);
}
input[type=text] { font-family: var(--font-mono); width: 100%; }
select:focus, input[type=text]:focus { outline: none; border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft); }

.hint { color: var(--muted); font-size: 0.77rem; margin: 0.2rem 0 0; min-height: 1em; }
.hint.err { color: var(--bad); }

input[type=range] {
  -webkit-appearance: none; appearance: none; width: 100%; height: 5px;
  background: var(--rule-h); border-radius: 999px; accent-color: var(--accent);
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none; width: 15px; height: 15px; border-radius: 999px;
  background: var(--accent); border: 2px solid var(--paper); cursor: pointer;
  box-shadow: var(--shadow-sm); }
input[type=range]::-moz-range-thumb {
  width: 15px; height: 15px; border-radius: 999px; background: var(--accent);
  border: 2px solid var(--paper); cursor: pointer; }

button.btn {
  background: linear-gradient(135deg, var(--accent), var(--accent-deep)); color: #fff; border: 0;
  padding: 0.5em 0.95em; border-radius: 8px; cursor: pointer; font-weight: 600;
  box-shadow: var(--shadow-sm); transition: filter .15s, transform .15s;
}
button.btn:hover { filter: brightness(1.07); transform: translateY(-1px); }
button.btn:active { transform: translateY(0); }

.readout {
  display: flex; justify-content: space-between; align-items: baseline;
  font-size: 0.83rem; padding-top: 0.32rem; border-top: 1px dotted var(--rule-h);
}
.readout span { color: var(--muted); }
.readout strong { color: var(--ink); font-weight: 700; font-family: var(--font-mono); }
.readout strong.big { font-size: 1.2rem; color: var(--accent-deep); }

.mono { font-family: var(--font-mono); font-weight: 500; }

/* editorial display headings for course/project section titles
   (these pages wrap sections in .demo and use these subhead classes) */
h1 { font-family: var(--font-display); font-weight: 600; letter-spacing: -0.015em; }
.mod-title, .s-title, .ac-name, .glossary .term dt, .split2 h3 {
  font-family: var(--font-display) !important; letter-spacing: -0.005em;
}
.mod-title { font-size: 1.06rem !important; }
.s-title { font-size: 1rem !important; }

/* FOOTER ---------------------------------------------------- */
footer {
  border-top: 1px solid var(--rule); margin-top: 1rem; padding: 1.2rem 1.6rem;
  display: flex; justify-content: space-between; font-size: 0.78rem; color: var(--muted);
  flex-wrap: wrap; gap: 0.5rem; font-family: var(--font-sans);
}
footer .more { display: flex; gap: 1rem; }
footer a { color: var(--muted); }
footer a:hover { color: var(--accent); }

/* KaTeX */
.katex { font-size: 0.97em; }