/* CXL Courseware — dark theme, extends the palette from the original index.html */
*, *::before, *::after { box-sizing: border-box; }
:root {
  --bg: #0f0f0f; --panel: #141414; --panel2: #1a1a1a; --border: #222;
  --border2: #2e2e2e; --text: #e0e0e0; --muted: #888; --dim: #555;
  --accent: #7eb8f7; --accent-bg: #0e1f33; --green: #34d399; --done: #052814;
}
html, body { margin: 0; height: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg); color: var(--text);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
button { font-family: inherit; cursor: pointer; }

/* ---------- layout ---------- */
.app { display: grid; grid-template-columns: 280px 1fr; height: 100vh; }
.sidebar {
  background: #0c0c0c; border-right: 1px solid var(--border);
  overflow-y: auto; padding: 1rem .75rem; display: flex; flex-direction: column;
}
.brand { font-size: 1.05rem; font-weight: 600; padding: .25rem .5rem 1rem; }
.brand small { display: block; color: var(--dim); font-weight: 400; font-size: .72rem; margin-top: .2rem; }
.nav-section { font-size: .68rem; text-transform: uppercase; letter-spacing: .06em;
  color: var(--dim); margin: 1rem .5rem .35rem; }
.nav-item {
  display: flex; align-items: center; gap: .5rem; padding: .4rem .5rem;
  border-radius: 6px; color: #bbb; font-size: .85rem; cursor: pointer;
  border: 1px solid transparent;
}
.nav-item:hover { background: var(--panel); text-decoration: none; }
.nav-item.active { background: var(--accent-bg); border-color: #1a3550; color: var(--accent); }
.nav-item .idx { color: var(--dim); font-size: .72rem; width: 1.3rem; flex-shrink: 0; }
.nav-item .pct { margin-left: auto; font-size: .68rem; color: var(--dim); }
.nav-spacer { flex: 1; }
.nav-user { color: var(--muted); font-size: .74rem; padding: .3rem .5rem; }
.nav-user strong { color: var(--text); font-weight: 600; }
.nav-logout { color: var(--dim); font-size: .78rem; padding: .5rem; background: none; border: none; text-align: left; }
.nav-logout:hover { color: var(--text); }

.main { overflow-y: auto; padding: 2rem 2.5rem; max-width: 1100px; }
.crumbs { font-size: .8rem; color: var(--dim); margin-bottom: 1rem; }
.crumbs a { color: var(--muted); }
h1 { font-size: 1.5rem; margin: 0 0 .4rem; }
h2 { font-size: 1.05rem; margin: 1.6rem 0 .6rem; }
.sub { color: var(--muted); font-size: .85rem; margin: 0 0 1.2rem; }

/* ---------- cards / lists ---------- */
.card {
  background: var(--panel); border: 1px solid var(--border); border-radius: 8px;
  margin-bottom: .5rem; overflow: hidden;
}
.row {
  display: flex; align-items: center; gap: .7rem; padding: .7rem .9rem;
  cursor: pointer; border-bottom: 1px solid #1c1c1c;
}
.row:last-child { border-bottom: none; }
.row:hover { background: var(--panel2); }
.row .title { flex: 1; font-size: .9rem; }
.row .meta { font-size: .72rem; color: var(--dim); white-space: nowrap; }
.row.section { cursor: default; background: #101010; }
.row.section .title { color: var(--muted); font-size: .78rem; text-transform: uppercase; letter-spacing: .04em; }
.row.section:hover { background: #101010; }

.tick { width: 18px; height: 18px; border-radius: 50%; border: 1.5px solid #333;
  flex-shrink: 0; display: grid; place-items: center; font-size: .7rem; color: transparent; }
.tick.done { background: var(--done); border-color: #0a4828; color: var(--green); }

.cat-progress { height: 4px; background: #1a1a1a; border-radius: 2px; overflow: hidden; margin-top: .3rem; }
.cat-progress > span { display: block; height: 100%; background: var(--accent); }

/* grid of category/course cards on home */
.tiles { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: .75rem; }
.tile {
  background: var(--panel); border: 1px solid var(--border); border-radius: 10px;
  padding: 1rem; cursor: pointer;
}
.tile:hover { border-color: #333; background: var(--panel2); }
.tile .idx { color: var(--dim); font-size: .72rem; }
.tile .name { font-size: 1rem; font-weight: 600; margin: .2rem 0 .5rem; }
.tile .meta { color: var(--muted); font-size: .78rem; }

/* ---------- lesson view ---------- */
.player {
  position: relative; width: 100%; aspect-ratio: 16/9; background: #000;
  border-radius: 10px; overflow: hidden; border: 1px solid var(--border);
}
.player iframe, .player embed, .player video { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; background: #000; }
.player .placeholder {
  position: absolute; inset: 0; display: grid; place-items: center; text-align: center;
  color: var(--dim); font-size: .85rem; padding: 2rem;
}
.lesson-head { display: flex; align-items: flex-start; gap: 1rem; margin: 1.2rem 0 .3rem; }
.lesson-head h1 { flex: 1; }
.btn {
  padding: .5rem .9rem; border-radius: 7px; border: 1px solid var(--border2);
  background: var(--panel2); color: var(--text); font-size: .82rem; white-space: nowrap;
}
.btn:hover { background: #242424; }
.btn.done { background: var(--done); border-color: #0a4828; color: var(--green); }

.lesson-nav { display: flex; justify-content: space-between; gap: .5rem; margin: 1.5rem 0; }

.notes-wrap { margin-top: 1.5rem; }
.notes-wrap label { font-size: .8rem; color: var(--muted); display: flex; justify-content: space-between; }
.notes-wrap textarea {
  width: 100%; min-height: 160px; margin-top: .4rem; padding: .75rem;
  background: var(--panel); border: 1px solid var(--border2); border-radius: 8px;
  color: var(--text); font-size: .9rem; line-height: 1.5; resize: vertical;
  font-family: inherit;
}
.save-state { font-size: .72rem; color: var(--dim); }

/* ---------- resource chips (from original index.html) ---------- */
.resources { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: 1rem; }
.chip { font-size: .76rem; padding: .25rem .6rem; border-radius: 5px; border: 1px solid; }
.chip:hover { text-decoration: underline; opacity: .85; }
.chip-default, .chip-slides     { color: #7eb8f7; background: #0e1f33; border-color: #1a3550; }
.chip-tool          { color: #c084fc; background: #1e1030; border-color: #3d2060; }
.chip-template      { color: #34d399; background: #05271a; border-color: #0a4030; }
.chip-article       { color: #fb923c; background: #281504; border-color: #4a2a08; }
.chip-documentation { color: #38bdf8; background: #041e2e; border-color: #083850; }
.chip-course        { color: #4ade80; background: #052814; border-color: #0a4828; }
.chip-transcript    { color: #94a3b8; background: #141820; border-color: #252d38; }
.chip-book          { color: #f472b6; background: #2a0a1a; border-color: #4a1030; }
.chip-text-lesson   { color: #ff6b6b; background: #2a1010; border-color: #5a2020; }

/* ---------- learning paths ---------- */
.phase { margin-bottom: 1.5rem; }
.phase-head { display: flex; align-items: center; gap: .6rem; margin-bottom: .5rem; }
.phase-num { width: 26px; height: 26px; border-radius: 50%; background: var(--accent-bg);
  border: 1px solid #1a3550; color: var(--accent); display: grid; place-items: center;
  font-size: .8rem; font-weight: 600; flex-shrink: 0; }
.phase-head h2 { margin: 0; font-size: 1rem; }
.path-bar { height: 8px; background: #1a1a1a; border-radius: 4px; overflow: hidden; margin: .5rem 0 1.5rem; }
.path-bar > span { display: block; height: 100%; background: linear-gradient(90deg, var(--accent), var(--green)); }
.path-meta { font-size: .8rem; color: var(--muted); }

#search {
  width: 100%; padding: .5rem .7rem; background: var(--panel2); border: 1px solid var(--border2);
  border-radius: 6px; color: var(--text); font-size: .85rem; margin: .25rem 0 1rem;
}
#search::placeholder { color: var(--dim); }
.empty { color: var(--dim); font-size: .85rem; padding: 2rem 0; }

/* video control bar (speed + shortcut hint) */
.vidbar { display: flex; align-items: center; flex-wrap: wrap; gap: .4rem; margin-top: .6rem; }
.vidbar-label { font-size: .75rem; color: var(--muted); margin-right: .2rem; }
.speed-btn {
  padding: .2rem .5rem; border-radius: 5px; border: 1px solid var(--border2);
  background: var(--panel2); color: var(--muted); font-size: .76rem;
}
.speed-btn:hover { color: var(--text); }
.speed-btn.active { background: var(--accent-bg); border-color: #1a3550; color: var(--accent); }
.vidbar-hint { margin-left: auto; font-size: .7rem; color: var(--dim); }

/* AI study tools */
.ai-panel { margin-top: 1.5rem; border: 1px solid var(--border2); border-radius: 10px; overflow: hidden; }
.ai-tabs { display: flex; gap: .25rem; padding: .5rem; background: var(--panel); border-bottom: 1px solid var(--border); }
.ai-tab { padding: .4rem .8rem; border-radius: 6px; border: 1px solid var(--border2);
  background: var(--panel2); color: var(--muted); font-size: .82rem; }
.ai-tab:hover { color: var(--text); }
.ai-tab.active { background: var(--accent-bg); border-color: #1a3550; color: var(--accent); }
.ai-body { padding: 1rem; min-height: 60px; }
.ai-hint { color: var(--dim); font-size: .8rem; }
.ai-loading { color: var(--accent); font-size: .85rem; }
.ai-err { color: #ff6b6b; font-size: .85rem; }
.ai-textblock { font-size: .9rem; line-height: 1.6; color: var(--text); }
.ai-ask { display: flex; gap: .5rem; margin-bottom: .8rem; }
.ai-ask input { flex: 1; padding: .5rem .7rem; background: var(--panel2);
  border: 1px solid var(--border2); border-radius: 7px; color: var(--text); font-size: .88rem; }
.quiz-q { margin-bottom: 1.1rem; }
.quiz-question { font-size: .9rem; font-weight: 500; margin-bottom: .5rem; }
.quiz-options { display: flex; flex-direction: column; gap: .35rem; }
.quiz-opt { text-align: left; padding: .45rem .7rem; border-radius: 6px;
  border: 1px solid var(--border2); background: var(--panel2); color: var(--text); font-size: .85rem; }
.quiz-opt:hover:not(:disabled) { background: #242424; }
.quiz-opt.correct { background: var(--done); border-color: #0a4828; color: var(--green); }
.quiz-opt.wrong { background: #2a1010; border-color: #5a2020; color: #ff6b6b; }
.quiz-exp { display: none; margin-top: .5rem; font-size: .82rem; color: var(--muted);
  padding: .5rem .7rem; background: var(--panel); border-radius: 6px; }
.quiz-exp.show { display: block; }

/* mobile drawer */
.menu-btn {
  display: none; position: fixed; top: .6rem; left: .6rem; z-index: 60;
  background: var(--panel); color: var(--text); border: 1px solid var(--border);
  border-radius: 7px; font-size: 1.1rem; width: 40px; height: 40px; cursor: pointer;
}
.overlay { display: none; }
@media (max-width: 820px) {
  .app { grid-template-columns: 1fr; }
  .menu-btn { display: block; }
  .sidebar {
    position: fixed; top: 0; left: 0; bottom: 0; width: 270px; z-index: 55;
    transform: translateX(-100%); transition: transform .2s ease;
  }
  .sidebar.open { transform: none; box-shadow: 0 0 40px rgba(0,0,0,.6); }
  .overlay.active {
    display: block; position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 54;
  }
  .main { padding: 3.5rem 1.1rem 2rem; }
  .vidbar-hint { display: none; }
}

/* ---------- login ---------- */
.login-screen { display: grid; place-items: center; height: 100vh; }
.login-box { width: 320px; background: var(--panel); border: 1px solid var(--border);
  border-radius: 12px; padding: 2rem; text-align: center; }
.login-box h1 { font-size: 1.2rem; margin-bottom: 1.2rem; }
.login-box input { width: 100%; padding: .6rem .8rem; background: var(--panel2);
  border: 1px solid var(--border2); border-radius: 7px; color: var(--text); font-size: .95rem; }
.login-box button { width: 100%; margin-top: .8rem; padding: .6rem; border-radius: 7px;
  border: none; background: var(--accent); color: #06121f; font-weight: 600; font-size: .9rem; }
.login-box .err { color: #ff6b6b; font-size: .8rem; margin-top: .7rem; min-height: 1rem; }