/* DeepInfer 101 — a local, CS61A-inspired course site. */

:root {
  --bg: #0e1116;
  --bg-soft: #131720;
  --panel: #171b24;
  --panel-2: #1d2230;
  --panel-3: #232938;
  --text: #e8ecf3;
  --muted: #9aa6b8;
  --muted-2: #6f7c90;
  --border: #2a3242;
  --border-soft: #212836;
  --accent: #5b8cff;
  --accent-2: #8fb2ff;
  --sidebar: #0a1730;
  --sidebar-2: #0d1f3f;
  --sidebar-text: #dce6f8;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.28);
  --radius: 14px;
  --radius-sm: 9px;

  --lecture: #4f8cff;
  --discussion: #f5c542;
  --lab: #f472b6;
  --homework: #34d399;
  --project: #2dd4bf;
  --reading: #a78bfa;
  --video: #fb923c;
  --quiz: #fbbf24;
  --exam: #f87171;
  --soon: #64748b;
}

[data-theme="light"] {
  --bg: #f5f7fb;
  --bg-soft: #eef2f8;
  --panel: #ffffff;
  --panel-2: #f6f8fc;
  --panel-3: #eef2f8;
  --text: #152033;
  --muted: #5b6b82;
  --muted-2: #7b8aa0;
  --border: #d9e1ec;
  --border-soft: #e6ecf4;
  --accent: #2f6fed;
  --accent-2: #2459c4;
  --sidebar: #0c2348;
  --sidebar-2: #10305f;
  --sidebar-text: #eaf1ff;
  --shadow: 0 18px 45px rgba(32, 55, 90, 0.12);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, "Segoe UI", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  line-height: 1.65;
  scroll-behavior: smooth;
}

body { min-height: 100vh; overflow-x: hidden; }

a { color: var(--accent-2); text-decoration: none; }
a:hover { text-decoration: underline; }

code, pre {
  font-family: "JetBrains Mono", "Cascadia Code", Consolas, "SFMono-Regular", monospace;
}

code {
  background: var(--panel-3);
  border: 1px solid var(--border-soft);
  border-radius: 5px;
  padding: 0.12em 0.38em;
  font-size: 0.92em;
}

pre {
  background: #0a0e15;
  color: #dbe7ff;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.55;
}

pre code {
  background: transparent;
  border: 0;
  padding: 0;
  color: inherit;
  font-size: inherit;
}

/* Layout */
.app {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: 262px;
  background: linear-gradient(180deg, var(--sidebar) 0%, var(--sidebar-2) 100%);
  color: var(--sidebar-text);
  padding: 22px 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 18px;
  border-right: 1px solid rgba(255, 255, 255, 0.08);
  z-index: 30;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 4px 8px 2px;
}

.brand-mark {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  font-weight: 800;
  letter-spacing: 0.5px;
  color: #08152c;
  background: linear-gradient(135deg, #9cc0ff, #5b8cff);
  box-shadow: 0 8px 20px rgba(91, 140, 255, 0.35);
}

.brand-title {
  font-weight: 800;
  font-size: 17px;
  letter-spacing: 0.2px;
}

.brand-sub {
  font-size: 11px;
  color: #93a7c8;
  letter-spacing: 0.4px;
  text-transform: uppercase;
}

.nav {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav a {
  color: #b9c8e2;
  padding: 9px 12px;
  border-radius: 9px;
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  transition: background 120ms ease, color 120ms ease;
}

.nav a:hover {
  background: rgba(255, 255, 255, 0.07);
  color: #fff;
  text-decoration: none;
}

.nav a.active {
  background: rgba(91, 140, 255, 0.2);
  color: #fff;
  box-shadow: inset 3px 0 0 #7ea6ff;
}

.nav .nav-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #5b8cff;
  opacity: 0.7;
}

.progress-card {
  margin-top: auto;
  background: rgba(255, 255, 255, 0.055);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 12px;
  padding: 12px 13px;
}

.progress-head {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: #b9c8e2;
  margin-bottom: 8px;
}

.progress-bar {
  height: 7px;
  border-radius: 99px;
  background: rgba(255, 255, 255, 0.12);
  overflow: hidden;
}

#progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #5b8cff, #7ef0d0);
  transition: width 220ms ease;
}

.link-btn {
  margin-top: 9px;
  padding: 0;
  border: 0;
  background: none;
  color: #93a7c8;
  font-size: 11px;
  cursor: pointer;
  text-decoration: underline;
}

.sidebar-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  font-size: 12px;
  color: #93a7c8;
}

.theme-btn {
  border: 1px solid rgba(255, 255, 255, 0.14);
  background: rgba(255, 255, 255, 0.06);
  color: #dce6f8;
  border-radius: 8px;
  padding: 7px 10px;
  cursor: pointer;
  font-size: 12px;
}

.theme-btn:hover { background: rgba(255, 255, 255, 0.11); }

.main {
  margin-left: 262px;
  width: calc(100% - 262px);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 34px;
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-soft);
}

.menu-btn {
  display: none;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 8px;
  padding: 7px 10px;
  cursor: pointer;
  font-size: 16px;
}

.crumbs {
  font-size: 13px;
  color: var(--muted);
  font-weight: 600;
  letter-spacing: 0.2px;
}

.top-actions {
  margin-left: auto;
  display: flex;
  gap: 8px;
}

.ghost-btn {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  border-radius: 8px;
  padding: 7px 11px;
  font-size: 12px;
  font-weight: 600;
}

.ghost-btn:hover { border-color: var(--accent); text-decoration: none; }

.content {
  width: min(1180px, 100%);
  margin: 0 auto;
  padding: 34px 34px 60px;
  flex: 1;
}

.footer {
  border-top: 1px solid var(--border-soft);
  color: var(--muted-2);
  font-size: 12px;
  padding: 22px 34px 28px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  justify-content: space-between;
}

/* Typography */
h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 0.55em; }
h1 { font-size: clamp(30px, 4vw, 46px); letter-spacing: -0.02em; }
h2 { font-size: 24px; letter-spacing: -0.01em; }
h3 { font-size: 17px; }
p { margin: 0 0 1em; }
.lede { font-size: 18px; color: var(--muted); max-width: 780px; overflow-wrap: anywhere; }
.muted { color: var(--muted); }
.small { font-size: 13px; }
.mono { font-family: "JetBrains Mono", "Cascadia Code", monospace; }

.eyebrow {
  display: inline-block;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 10px;
}

.page-head {
  margin-bottom: 26px;
}

.page-head h1 { margin-bottom: 8px; }
.page-head p { max-width: 820px; color: var(--muted); }

/* Hero */
.hero {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 20px;
  background:
    radial-gradient(900px 380px at 12% -10%, rgba(91, 140, 255, 0.26), transparent 60%),
    radial-gradient(700px 340px at 88% 10%, rgba(45, 212, 191, 0.14), transparent 60%),
    var(--panel);
  padding: 38px 38px 32px;
  box-shadow: var(--shadow);
  margin-bottom: 26px;
}

.hero h1 { max-width: 900px; }
.hero .lede { font-size: 18px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 20px; }

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--border-soft);
  color: var(--muted);
  font-size: 13px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 15px;
  font-weight: 700;
  font-size: 14px;
  cursor: pointer;
  transition: transform 100ms ease, border-color 120ms ease, background 120ms ease;
}

.btn:hover { text-decoration: none; border-color: var(--accent); transform: translateY(-1px); }
.btn.primary {
  background: linear-gradient(135deg, #5b8cff, #3a6df0);
  border-color: transparent;
  color: #fff;
  box-shadow: 0 10px 24px rgba(58, 109, 240, 0.3);
}
.btn.small { padding: 7px 11px; font-size: 12px; }
.btn.ghost { background: transparent; }

/* Cards / grids */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin: 18px 0 30px;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin: 18px 0 30px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}

.card h3 { margin-bottom: 6px; }
.card p { color: var(--muted); font-size: 14px; margin-bottom: 0; }
.card .card-kicker {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted-2);
  margin-bottom: 8px;
}

.section-title {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  margin: 34px 0 14px;
}

.section-title h2 { margin: 0; }
.section-title a { font-size: 13px; }

.announcement {
  display: grid;
  grid-template-columns: 92px 1fr;
  gap: 14px;
  padding: 13px 0;
  border-bottom: 1px solid var(--border-soft);
}

.announcement:last-child { border-bottom: 0; }
.announcement .date {
  color: var(--muted-2);
  font-size: 12px;
  font-family: "JetBrains Mono", monospace;
  padding-top: 2px;
}
.announcement .body { font-size: 14px; color: var(--muted); overflow-wrap: anywhere; }
.announcement .body strong { color: var(--text); }

/* Badges */
.badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 20px;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  white-space: nowrap;
  color: #08111f;
}

.badge.lecture { background: var(--lecture); }
.badge.discussion { background: var(--discussion); }
.badge.lab { background: var(--lab); }
.badge.homework { background: var(--homework); }
.badge.project { background: var(--project); }
.badge.reading { background: var(--reading); }
.badge.video { background: var(--video); }
.badge.quiz { background: var(--quiz); }
.badge.exam { background: var(--exam); }
.badge.soon { background: var(--soon); color: #fff; }

/* Calendar */
.calendar-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  margin: 16px 0 22px;
}

.search {
  flex: 1 1 320px;
  min-width: 220px;
  background: var(--panel);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 13px;
  font-size: 14px;
  outline: none;
}

.search:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(91, 140, 255, 0.16); }

.week-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 18px;
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.08);
}

.week-card.current {
  border-color: rgba(91, 140, 255, 0.7);
  box-shadow: 0 0 0 2px rgba(91, 140, 255, 0.12), 0 12px 30px rgba(0, 0, 0, 0.14);
}

.week-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
  padding: 17px 20px;
  background: linear-gradient(180deg, var(--panel-2), transparent);
  border-bottom: 1px solid var(--border-soft);
}

.week-kicker {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-2);
}

.week-head h2 { font-size: 19px; margin: 3px 0 0; }
.week-dates {
  font-size: 12px;
  color: var(--muted-2);
  font-family: "JetBrains Mono", monospace;
  white-space: nowrap;
  padding-top: 5px;
}

.week-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 270px;
  gap: 0;
}

.week-main { padding: 8px 0 8px 8px; }
.intro-practice { padding: 8px 12px; font-size: 14px; color: var(--muted); }
.week-side {
  border-left: 1px solid var(--border-soft);
  padding: 12px 16px;
  background: color-mix(in srgb, var(--panel-2) 55%, transparent);
}

.item {
  display: grid;
  grid-template-columns: 22px 112px minmax(0, 1fr);
  align-items: start;
  gap: 10px;
  padding: 7px 12px;
  border-radius: 9px;
}

.item:hover { background: var(--panel-2); }
.item.done .item-link { color: var(--muted-2); text-decoration: line-through; }

.item-check {
  appearance: none;
  width: 16px;
  height: 16px;
  margin-top: 4px;
  border: 1.5px solid var(--border);
  border-radius: 5px;
  background: transparent;
  cursor: pointer;
  position: relative;
}

.item-check:checked {
  background: var(--accent);
  border-color: var(--accent);
}

.item-check:checked::after {
  content: "✓";
  position: absolute;
  inset: -3px 0 0 2px;
  color: #fff;
  font-size: 12px;
  font-weight: 900;
}

.item-link {
  color: var(--text);
  font-size: 14px;
  font-weight: 600;
  overflow-wrap: anywhere;
}

.item-link:hover { color: var(--accent-2); }
.item-note { color: var(--muted-2); font-size: 12px; font-weight: 400; }

.side-label {
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted-2);
  margin: 0 0 8px;
}

.side-item {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 5px 0;
  font-size: 13px;
}

.side-item a { color: var(--muted); }
.side-item a:hover { color: var(--accent-2); }

.week-empty {
  padding: 18px;
  color: var(--muted-2);
  font-size: 13px;
}

/* Textbook */
.textbook-layout {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 28px;
  align-items: start;
}

.toc {
  position: sticky;
  top: 82px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
}

.toc h3 {
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted-2);
  margin-bottom: 10px;
}

.toc button {
  display: block;
  width: 100%;
  text-align: left;
  border: 0;
  background: none;
  color: var(--muted);
  font-size: 12px;
  padding: 6px 8px;
  border-radius: 7px;
  cursor: pointer;
}

.toc button:hover { background: var(--panel-2); color: var(--text); }

.chapter {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 18px;
  scroll-margin-top: 86px;
}

.chapter-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 8px;
}

.chapter-num {
  font-family: "JetBrains Mono", monospace;
  font-size: 12px;
  font-weight: 800;
  color: var(--accent-2);
  background: rgba(91, 140, 255, 0.12);
  border: 1px solid rgba(91, 140, 255, 0.25);
  border-radius: 6px;
  padding: 2px 7px;
}

.chapter h2 { font-size: 21px; margin: 0; }
.chapter-intro { color: var(--muted); }

.understanding {
  border-left: 3px solid var(--accent);
  background: color-mix(in srgb, var(--accent) 7%, transparent);
  border-radius: 0 10px 10px 0;
  padding: 13px 16px;
  margin: 16px 0;
}

.understanding h3 {
  font-size: 12px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 6px;
}

.understanding p { margin: 0; font-size: 14px; }

.key-points {
  margin: 14px 0;
  padding-left: 20px;
  color: var(--muted);
  font-size: 14px;
}

.key-points li { margin: 5px 0; }

.chapter-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  border-radius: 999px;
  padding: 5px 10px;
  font-size: 12px;
}

.chip:hover { border-color: var(--accent); text-decoration: none; }

.formula {
  background: #0a0e15;
  color: #dbe7ff;
  border: 1px solid var(--border);
  border-radius: 9px;
  padding: 12px 14px;
  font-family: "JetBrains Mono", monospace;
  font-size: 12px;
  overflow-x: auto;
  white-space: pre-wrap;
}

.question-group {
  border-bottom: 1px solid var(--border-soft);
  padding: 10px 0;
}

.question-group:last-child { border-bottom: 0; }

.question-group summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 14px;
  color: var(--text);
}

.question-group summary:hover { color: var(--accent-2); }

.question-group ol {
  margin: 12px 0 4px 22px;
  color: var(--muted);
  font-size: 14px;
}

.question-group li { margin: 5px 0; }

.card .chip { margin: 4px 4px 0 0; }

/* Resources */
.resource-group { margin-bottom: 28px; }
.resource-group h2 { font-size: 20px; margin-bottom: 4px; }
.resource-group > p { color: var(--muted); font-size: 14px; margin-bottom: 12px; }

.resource-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.resource {
  display: flex;
  flex-direction: column;
  gap: 3px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 13px 14px;
  transition: border-color 120ms ease, transform 100ms ease;
}

.resource:hover { border-color: var(--accent); transform: translateY(-1px); text-decoration: none; }
.resource .r-title { font-weight: 700; font-size: 14px; color: var(--text); }
.resource .r-desc { font-size: 12px; color: var(--muted); }
.resource .r-tag { font-size: 10px; color: var(--muted-2); text-transform: uppercase; letter-spacing: 0.1em; }

/* Videos */
.video-path {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 14px;
  border: 1px solid var(--border);
  background: var(--panel);
  border-radius: 12px;
  padding: 12px 16px;
  margin: 18px 0 26px;
  font-size: 13px;
}

.video-path span {
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted-2);
}

.video-path strong { color: var(--text); font-size: 13px; }

.video-group { margin-bottom: 30px; }
.video-group h2 { font-size: 21px; margin-bottom: 4px; }
.video-group > p { color: var(--muted); font-size: 14px; margin-bottom: 12px; }

.video-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.video-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 17px 18px;
  transition: border-color 120ms ease, transform 100ms ease;
}

.video-card:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
  text-decoration: none;
}

.video-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.video-level {
  font-size: 10px;
  font-weight: 700;
  color: var(--muted-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 2px 8px;
}

.video-card h3 {
  font-size: 15px;
  line-height: 1.45;
  color: var(--text);
  margin: 0;
}

.video-meta {
  font-size: 11px;
  color: var(--muted-2);
  font-family: "JetBrains Mono", monospace;
}

.video-card p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.65;
}

.video-watch {
  margin-top: 2px;
  padding: 8px 10px;
  border-left: 2px solid var(--video);
  border-radius: 0 8px 8px 0;
  background: var(--panel-2);
  color: var(--muted);
  font-size: 12px;
  line-height: 1.6;
}

.video-watch strong { color: var(--text); }

/* Syllabus / sections */
.prose {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px;
}
.prose h2 { margin-top: 26px; font-size: 20px; }
.prose h2:first-child { margin-top: 0; }
.prose h3 { margin-top: 18px; }
.prose p, .prose li { color: var(--muted); font-size: 14px; }
.prose strong { color: var(--text); }
.prose table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 13px; }
.prose th, .prose td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border-soft); }
.prose th { color: var(--muted-2); font-size: 11px; text-transform: uppercase; letter-spacing: 0.08em; }
.prose code { white-space: nowrap; }

.section-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  margin-bottom: 14px;
}

.section-card h2 { font-size: 19px; }
.section-card .goals { color: var(--muted); font-size: 14px; }
.section-card ol { color: var(--muted); font-size: 14px; padding-left: 22px; }
.section-card li { margin: 6px 0; }

/* Staff */
.staff-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.staff-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
}

.avatar {
  width: 52px;
  height: 52px;
  border-radius: 15px;
  display: grid;
  place-items: center;
  font-size: 24px;
  background: var(--panel-3);
  border: 1px solid var(--border);
  margin-bottom: 12px;
}

.staff-card h3 { margin-bottom: 2px; }
.staff-card .role { color: var(--accent-2); font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; }
.staff-card p { color: var(--muted); font-size: 14px; margin-top: 10px; }

/* Contact */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.callout {
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  background: var(--panel);
  border-radius: 0 12px 12px 0;
  padding: 16px 18px;
  margin: 16px 0;
}

.callout p:last-child { margin-bottom: 0; }

/* Misc */
.hr { height: 1px; background: var(--border-soft); border: 0; margin: 28px 0; }
.kbd {
  font-family: "JetBrains Mono", monospace;
  font-size: 11px;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 5px;
  padding: 1px 5px;
  background: var(--panel-2);
}
.hidden { display: none !important; }

/* Responsive */
@media (max-width: 1050px) {
  .grid-3, .staff-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .week-grid { grid-template-columns: 1fr; }
  .week-side { border-left: 0; border-top: 1px solid var(--border-soft); }
  .textbook-layout { grid-template-columns: 1fr; }
  .toc { position: static; }
}

@media (max-width: 820px) {
  .sidebar {
    transform: translateX(-100%);
    transition: transform 180ms ease;
    visibility: hidden;
    box-shadow: none;
  }
  .sidebar.open { transform: translateX(0); visibility: visible; box-shadow: 24px 0 60px rgba(0, 0, 0, 0.35); }
  .main { margin-left: 0; width: 100%; }
  .menu-btn { display: inline-flex; }
  .topbar { padding: 12px 18px; }
  .content { padding: 24px 18px 48px; }
  .grid-3, .grid-2, .staff-grid, .resource-grid, .contact-grid, .video-grid { grid-template-columns: 1fr; }
  .hero { padding: 26px 22px; }
  .item { grid-template-columns: 22px 96px minmax(0, 1fr); }
  .week-head { flex-direction: column; gap: 4px; }
}

@media (max-width: 640px) {
  .top-actions .ghost-btn:nth-child(2) { display: none; }
  .hero-actions .btn { flex: 1 1 100%; }
  .announcement { grid-template-columns: 1fr; gap: 4px; }
  .announcement .date { padding-top: 0; }
}

@media (max-width: 520px) {
  .hero h1 { font-size: 30px; }
  .item { grid-template-columns: 22px 1fr; }
  .item .badge { grid-column: 2; justify-self: start; }
  .item > div { grid-column: 2; min-width: 0; }
  .item-link { overflow-wrap: anywhere; }
  .chapter { padding: 18px; }
  .prose { padding: 18px; }
}

/* ------------------------------------------------------------------
   Rendered note pages (course/site/notes/*.html)
   ------------------------------------------------------------------ */
.doc-body {
  background:
    radial-gradient(900px 420px at 82% -8%, rgba(91, 140, 255, 0.12), transparent 60%),
    var(--bg);
}

.doc-topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 13px 28px;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-soft);
}

.doc-back {
  color: var(--accent-2);
  font-size: 13px;
  font-weight: 700;
  white-space: nowrap;
}

.doc-category {
  white-space: nowrap;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px 9px;
}

.doc-brand {
  margin-left: auto;
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
}

.doc-topbar .theme-btn {
  white-space: nowrap;
  color: var(--text);
  background: var(--panel-2);
  border-color: var(--border);
}

.doc-main {
  width: min(1180px, 100%);
  margin: 0 auto;
  padding: 30px 28px 60px;
}

.doc-hero {
  border: 1px solid var(--border);
  border-radius: 18px;
  background:
    radial-gradient(700px 300px at 8% -20%, rgba(91, 140, 255, 0.22), transparent 60%),
    var(--panel);
  padding: 30px 32px;
  box-shadow: var(--shadow);
}

.doc-hero h1 {
  font-size: clamp(28px, 3.6vw, 42px);
  margin-bottom: 10px;
}

.doc-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  color: var(--muted);
  font-size: 13px;
}

.doc-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 18px;
}

.doc-done {
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  border-radius: 9px;
  padding: 8px 14px;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
}

.doc-done:hover { border-color: var(--accent); }
.doc-done.done {
  background: var(--homework);
  border-color: transparent;
  color: #08111f;
}

.doc-hint { font-size: 12px; color: var(--muted-2); }

.doc-layout {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 24px;
  align-items: start;
  margin-top: 24px;
}

.doc-toc {
  position: sticky;
  top: 78px;
  max-height: calc(100vh - 108px);
  overflow-y: auto;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
}

.doc-toc h3 {
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted-2);
  margin-bottom: 8px;
}

.doc-toc > summary { cursor: pointer; color: var(--text); font-size: 13px; font-weight: 700; }
.doc-toc[open] > summary { margin-bottom: 10px; }
.doc-toc > nav { padding-top: 2px; }

.doc-toc a {
  display: block;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.5;
  padding: 4px 7px;
  border-radius: 6px;
}

.doc-toc a:hover { background: var(--panel-2); color: var(--text); text-decoration: none; }
.doc-toc .toc-level-3 { padding-left: 18px; font-size: 11px; }

.doc-content {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 34px;
  min-width: 0;
}

.doc-content h1 { font-size: 30px; }
.doc-content h2 {
  font-size: 22px;
  margin-top: 32px;
  padding-top: 14px;
  border-top: 1px solid var(--border-soft);
}
.doc-content h2:first-child { margin-top: 0; padding-top: 0; border-top: 0; }
.doc-content h3 { font-size: 17px; margin-top: 24px; }
.doc-content h4 { font-size: 15px; margin-top: 18px; }

.doc-content p,
.doc-content li {
  color: var(--muted);
  font-size: 15px;
  line-height: 1.85;
}

.doc-content strong { color: var(--text); }
.doc-content ul, .doc-content ol { padding-left: 24px; margin: 10px 0 16px; }
.doc-content li { margin: 4px 0; }
.doc-content hr { border: 0; height: 1px; background: var(--border-soft); margin: 26px 0; }

.doc-content blockquote {
  margin: 16px 0;
  padding: 12px 16px;
  border-left: 3px solid var(--accent);
  background: color-mix(in srgb, var(--accent) 7%, transparent);
  border-radius: 0 10px 10px 0;
}

.doc-content blockquote p { margin: 0; }

.doc-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 14px;
}

.doc-content th,
.doc-content td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border-soft);
  color: var(--muted);
  vertical-align: top;
}

.doc-content th {
  color: var(--muted-2);
  font-size: 11px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.doc-content pre { margin: 16px 0; }
.doc-content { min-width: 0; overflow-wrap: anywhere; }
.doc-content table { display: block; overflow-x: auto; }
.practice-list { display: grid; gap: 18px; }
#storage-status { padding: 0 24px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.doc-content img { max-width: 100%; border-radius: 10px; }
.textbook-figure { margin: 24px 0; padding: 12px; border: 1px solid var(--border); border-radius: 12px; background: var(--panel-2); }
.textbook-figure > a { display: block; text-align: center; overflow-x: auto; }
.textbook-figure img { display: block; width: 100%; min-width: 520px; max-width: 640px; height: auto; margin: 0 auto; background: #f8fafc; }
.textbook-figure figcaption { margin-top: 12px; font-size: 13px; line-height: 1.7; color: var(--muted); }
.figure-zoom { display: block; font-size: 12px; color: var(--accent); margin-top: 4px; }
.doc-content h2, .doc-content h3 { scroll-margin-top: 84px; }

.doc-content .study-hint {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 16px;
  margin: 14px 0;
  background: var(--panel-2);
}
.study-hint > summary { cursor: pointer; color: var(--accent-2); font-weight: 700; }
.study-hint > summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
.study-hint[open] > summary { margin-bottom: 12px; }
@media print {
  .study-hint::details-content { display: block; }
}

.doc-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-top: 24px;
}

.doc-nav-card {
  display: flex;
  flex-direction: column;
  gap: 4px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 14px 16px;
}

.doc-nav-card span { font-size: 11px; color: var(--muted-2); text-transform: uppercase; letter-spacing: 0.08em; }
.doc-nav-card strong { font-size: 14px; color: var(--text); }
.doc-nav-card:hover { border-color: var(--accent); text-decoration: none; }
.doc-nav-card.disabled { opacity: 0.45; }

@media (max-width: 900px) {
  .doc-layout { grid-template-columns: 1fr; }
  .doc-toc { position: static; max-height: none; }
  .doc-content { padding: 22px 18px; }
  .doc-topbar { padding: 12px 16px; }
  .doc-main { padding: 20px 16px 40px; }
  .doc-nav { grid-template-columns: 1fr; }
}

@media print {
  .doc-topbar, .doc-toc, .doc-actions, .doc-nav { display: none !important; }
  .doc-main { width: 100%; padding: 0; }
  .doc-content, .doc-hero { border: 0; box-shadow: none; }
  .textbook-figure img { min-width: 0; }
}

@media (max-width: 520px) {
  .doc-topbar { flex-wrap: wrap; gap: 10px; }
  .doc-brand { display: none; }
  .doc-topbar .theme-btn { margin-left: auto; }
  .textbook-figure::before { content: "↔ 左右滑动查看完整图解"; display: block; margin-bottom: 10px; color: var(--accent); font-size: 12px; }
}