/* 02805 course site — layout & typography.
   Faces: Space Grotesk (display) · IBM Plex Sans (body) · IBM Plex Mono (utility). */

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}

body {
  margin: 0;
  background: var(--page);
  color: var(--text-primary);
  font-family: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.65;
}

/* ---------- shell ---------- */

.wrap { max-width: 880px; margin: 0 auto; padding: 0 24px; }

.site-nav {
  display: flex; align-items: baseline; gap: 20px;
  padding: 20px 24px; max-width: 880px; margin: 0 auto;
  font-family: "IBM Plex Mono", ui-monospace, monospace;
  font-size: 13px;
}
.site-nav .brand { color: var(--text-primary); font-weight: 600; text-decoration: none; }
.site-nav a { color: var(--text-secondary); text-decoration: none; }
.site-nav a:hover { color: var(--accent); }
.site-nav .spacer { flex: 1; }

footer {
  margin-top: 96px; padding: 32px 24px 48px;
  border-top: 1px solid var(--grid);
  color: var(--text-muted); font-size: 14px;
}
footer .wrap { display: flex; gap: 24px; flex-wrap: wrap; }
footer a { color: var(--text-secondary); }

/* ---------- type ---------- */

h1, h2, h3 {
  font-family: "Space Grotesk", "IBM Plex Sans", system-ui, sans-serif;
  line-height: 1.15; letter-spacing: -0.015em;
}
h1 { font-size: clamp(2.1rem, 5.5vw, 3.4rem); font-weight: 700; margin: 0.2em 0 0.35em; }
h2 { font-size: 1.65rem; font-weight: 600; margin: 2.6em 0 0.6em; }
h3 { font-size: 1.15rem; font-weight: 600; margin: 2em 0 0.5em; }

p, li { color: var(--text-secondary); }
strong { color: var(--text-primary); }
a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }

.eyebrow {
  font-family: "IBM Plex Mono", ui-monospace, monospace;
  font-size: 12.5px; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--text-muted); margin: 0;
}

.lede { font-size: 1.2rem; line-height: 1.55; color: var(--text-secondary); max-width: 620px; }

code, .mono { font-family: "IBM Plex Mono", ui-monospace, monospace; font-size: 0.88em; }
code { background: var(--surface-1); border: 1px solid var(--grid); border-radius: 4px; padding: 0.08em 0.35em; }

/* ---------- hero (front page) ---------- */

.hero { position: relative; padding: 48px 0 40px; overflow: hidden; }
.hero canvas {
  position: absolute; inset: 0; width: 100%; height: 100%;
  z-index: 0; opacity: 0.9;
}
.hero .wrap { position: relative; z-index: 1; }
.thesis {
  font-family: "Space Grotesk", system-ui, sans-serif;
  font-size: 1.25rem; font-weight: 500; color: var(--text-primary);
  border-left: 3px solid var(--accent); padding-left: 16px; max-width: 560px;
}

/* ---------- cards & tables ---------- */

.card-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 16px; margin: 24px 0; }
.card {
  background: var(--surface-1); border: 1px solid var(--grid); border-radius: 10px;
  padding: 20px 22px;
}
.card h3 { margin-top: 0; }
.card p { font-size: 15.5px; margin-bottom: 0; }

table.plain {
  width: 100%; border-collapse: collapse; font-size: 15.5px; margin: 20px 0;
}
table.plain th {
  text-align: left; font-family: "IBM Plex Mono", ui-monospace, monospace;
  font-size: 12.5px; letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--text-muted); font-weight: 500;
  border-bottom: 1px solid var(--baseline); padding: 8px 12px 8px 0;
}
table.plain td { border-bottom: 1px solid var(--grid); padding: 9px 12px 9px 0; color: var(--text-secondary); vertical-align: top; }
table.plain td:first-child { white-space: nowrap; }

/* ---------- mode badges ---------- */

.mode {
  display: inline-block; font-family: "IBM Plex Mono", ui-monospace, monospace;
  font-size: 12px; font-weight: 600; letter-spacing: 0.05em;
  border-radius: 999px; padding: 2px 10px; vertical-align: 1px; white-space: nowrap;
}
.mode.learn      { color: var(--mode-learn);      background: var(--mode-learn-wash); }
.mode.instrument { color: var(--mode-instrument); background: var(--mode-instrument-wash); }
.mode.builder    { color: var(--mode-builder);    background: var(--mode-builder-wash); }

/* ---------- week pages ---------- */

.explorable-frame {
  width: 100%; border: 1px solid var(--grid); border-radius: 10px;
  background: var(--surface-1); margin: 12px 0 6px;
}
.explorable-caption { font-size: 14px; color: var(--text-muted); margin: 4px 0 28px; }

.reading, .exercise {
  background: var(--surface-1); border: 1px solid var(--grid); border-radius: 10px;
  padding: 18px 22px; margin: 18px 0;
}
.exercise h4 { margin: 0 0 6px; font-size: 1.02rem; font-family: "Space Grotesk", system-ui, sans-serif; }
.exercise p, .exercise li { font-size: 15.5px; }
.exercise ol, .exercise ul { padding-left: 22px; }

.on-the-test, .callout {
  border-left: 3px solid var(--accent); background: var(--accent-wash);
  border-radius: 0 10px 10px 0; padding: 16px 22px; margin: 28px 0;
}
.on-the-test .eyebrow, .callout .eyebrow { color: var(--accent); }
.on-the-test p, .on-the-test li, .callout p { font-size: 15.5px; }
.callout p:last-child { margin-bottom: 4px; }

blockquote {
  margin: 20px 0; padding: 2px 0 2px 20px;
  border-left: 3px solid var(--baseline);
  color: var(--text-secondary); font-style: italic;
}
blockquote p { margin: 0 0 10px; }
blockquote p:last-child { margin-bottom: 0; }
blockquote em { font-style: normal; }

.video-embed { aspect-ratio: 16 / 9; width: 100%; border: 1px solid var(--grid); border-radius: 10px; margin: 12px 0 6px; }
.figure { margin: 12px 0 6px; }
.figure img { display: block; width: 100%; border: 1px solid var(--grid); border-radius: 10px; }

/* ---------- weeks grid (front page) ---------- */

.weeks { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 14px; margin: 24px 0; }
.week-card {
  display: block; text-decoration: none;
  background: var(--surface-1); border: 1px solid var(--grid); border-radius: 10px;
  padding: 16px 18px; color: var(--text-secondary);
}
.week-card .num { font-family: "IBM Plex Mono", ui-monospace, monospace; font-size: 12px; color: var(--text-muted); display: block; }
.week-card .title { font-family: "Space Grotesk", system-ui, sans-serif; font-weight: 600; color: var(--text-primary); font-size: 1.02rem; }
.week-card.live { border-color: var(--accent); }
.week-card.live:hover { background: var(--accent-wash); }
.week-card.soon { opacity: 0.62; }
.week-card .status { font-size: 12.5px; color: var(--text-muted); }
.week-card.live .status { color: var(--accent); }

/* focus visibility */
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px;
}

pre {
  background: var(--surface-1); border: 1px solid var(--grid); border-radius: 10px;
  padding: 14px 18px; overflow-x: auto; font-size: 0.88rem; line-height: 1.55;
  margin: 16px 0 24px;
}
pre code { background: none; border: none; padding: 0; font-size: inherit; }

/* ---------- floating page TOC (wide screens only) ---------- */

h2 { scroll-margin-top: 24px; }

.page-toc {
  display: none; position: fixed; top: 110px;
  left: calc(50% + 452px); width: 184px;
  font-family: "IBM Plex Mono", ui-monospace, monospace; font-size: 12.5px;
  max-height: calc(100vh - 150px); overflow-y: auto;
}
@media (min-width: 1310px) { .page-toc { display: block; } }
.page-toc .toc-title {
  font-size: 11.5px; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--text-muted); margin: 0 0 10px;
}
.page-toc ol { list-style: none; margin: 0; padding: 0; }
.page-toc li { margin: 0 0 8px; line-height: 1.4; }
.page-toc a { color: var(--text-muted); text-decoration: none; display: block; }
.page-toc a:hover { color: var(--text-secondary); }
.page-toc a.active { color: var(--accent); }

/* ---------- essentials band ---------- */

.band-essentials {
  margin: 72px calc(50% - 50vw) 72px; padding: 2px calc(50vw - 50%) 44px;
  background: var(--essentials-bg);
}
.band-essentials p, .band-essentials li,
.band-essentials dt, .band-essentials dd {
  font-family: "IBM Plex Serif", Georgia, serif;
}
.band-essentials h2 { margin-top: 1.8em; color: var(--essentials-ink); }
.band-essentials p, .band-essentials li, .band-essentials dd { color: var(--essentials-ink-2); }
.band-essentials strong { color: var(--essentials-ink); }
.band-essentials a { color: var(--essentials-accent); }
.band-essentials .eyebrow { color: var(--essentials-muted); }
.band-essentials .on-the-test {
  background: var(--essentials-wash); border-left-color: var(--essentials-accent);
}
.band-essentials .on-the-test .eyebrow { color: var(--essentials-accent); }
.band-essentials code {
  background: var(--essentials-wash); border-color: var(--essentials-grid);
  color: var(--essentials-ink);
}

dl.defs { margin: 24px 0 8px; }
dl.defs dt { font-weight: 600; color: var(--essentials-ink); }
dl.defs dd { margin: 2px 0 14px; font-size: 15.5px; }