/* ════════════════════════════════════════════════════════════════
   TeqStudy — Design System
   One shared stylesheet driving every section of index.html.
   Extracted from the "High Voltage" reference: dark dashboard palette,
   cyan/amber/green accents, glass cards, conic-gradient rings.
   ════════════════════════════════════════════════════════════════ */

:root {
  /* Core surface tokens (reference names, kept exact) */
  --bg: #0b0f1a;
  --bg-elevated: #121826;
  --bg-card: #161e2e;
  --bg-card-hover: #1c2638;
  --border: #243044;
  --border-soft: #1e2a3d;
  --text: #e8eef7;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --primary: #38bdf8;
  --primary-soft: rgba(56, 189, 248, 0.15);
  --accent: #fbbf24;
  --accent-soft: rgba(251, 191, 36, 0.15);
  --success: #34d399;
  --purple: #a78bfa;
  --radius: 16px;
  --radius-sm: 12px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);

  /* Legacy names still referenced inline throughout index.html
     (--tc:var(--orange) etc.) — mapped onto the new palette so
     every existing track-pill / course-card color-codes correctly
     without any HTML changes. */
  --orange: #fbbf24;
  --orange-dim: rgba(251, 191, 36, 0.15);
  --orange-glow: rgba(251, 191, 36, 0.35);
  --green: #34d399;
  --teal: #38bdf8;
  --muted: var(--text-muted);
  --soft: var(--text-secondary);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(56, 189, 248, 0.12), transparent),
    radial-gradient(ellipse 60% 40% at 80% 20%, rgba(251, 191, 36, 0.06), transparent);
  background-attachment: fixed;
}

a { color: inherit; }

/* ── HERO ─────────────────────────────────────── */
.hero {
  max-width: 900px;
  margin: 0 auto;
  padding: 90px 24px 60px;
  text-align: center;
}

.hero-eyebrow {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--primary);
  background: var(--primary-soft);
  border: 1px solid rgba(56, 189, 248, 0.3);
  border-radius: 20px;
  padding: 6px 14px;
  margin-bottom: 24px;
}

.hero-title {
  font-size: clamp(38px, 6vw, 64px);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -1px;
}

.hero-title .accent {
  background: linear-gradient(135deg, var(--accent), #f59e0b);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-title .dim { color: var(--text-muted); }

.hero-sub {
  max-width: 620px;
  margin: 22px auto 0;
  color: var(--text-secondary);
  font-size: 17px;
  line-height: 1.6;
}

/* Terminal-style compile widget, restyled as a bg-card */
.compile-widget {
  max-width: 560px;
  margin: 36px auto 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  text-align: left;
}

.compile-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border-soft);
}

.dot { width: 10px; height: 10px; border-radius: 50%; }
.dot-r { background: #f87171; }
.dot-y { background: var(--accent); }
.dot-g { background: var(--success); }

.compile-label {
  margin-left: 8px;
  font-family: 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 12px;
  color: var(--text-muted);
}

.compile-body {
  padding: 18px 20px;
  min-height: 84px;
  font-family: 'Fira Code', 'JetBrains Mono', monospace;
  font-size: 13px;
  line-height: 1.7;
  color: var(--text-secondary);
}

.hero-cta { margin-top: 32px; }

.cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: linear-gradient(135deg, var(--accent), #f59e0b);
  color: #0b0f1a;
  font-weight: 600;
  font-size: 15px;
  padding: 13px 26px;
  border-radius: 10px;
  text-decoration: none;
  transition: all 0.2s ease;
  box-shadow: 0 4px 20px rgba(251, 191, 36, 0.3);
}

.cta-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(251, 191, 36, 0.42);
}

/* Stats row — small stat cards, conic-ring flavor kept subtle */
.stats-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 28px;
  margin-top: 44px;
  flex-wrap: wrap;
}

.stat { text-align: center; }

.stat-num {
  font-size: 32px;
  font-weight: 700;
  letter-spacing: -0.5px;
  background: linear-gradient(90deg, var(--text), var(--text-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  margin-top: 4px;
  font-size: 12px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.stat-div {
  width: 1px;
  height: 32px;
  background: var(--border);
}

/* ── SECTION HEADERS ──────────────────────────── */
.roadmap-section {
  max-width: 1180px;
  margin: 0 auto;
  padding: 64px 24px 8px;
}

.section-header { margin-bottom: 32px; }

.section-eyebrow {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--primary);
  font-family: 'Fira Code', 'JetBrains Mono', monospace;
  margin-bottom: 8px;
}

.section-title {
  font-size: 30px;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.section-sub {
  margin-top: 8px;
  color: var(--text-secondary);
  font-size: 15px;
  max-width: 640px;
}

/* ── TRACK NAV PILLS ──────────────────────────── */
.track-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 36px;
}

.track-pill {
  --tc: var(--primary);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: 10px;
  padding: 9px 15px;
  text-decoration: none;
  transition: all 0.18s ease;
}

.track-pill:hover {
  color: var(--tc);
  border-color: var(--tc);
  background: var(--bg-card-hover);
  transform: translateY(-1px);
}

/* ── TRACK OVERVIEW GRID ──────────────────────── */
.track-overview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-bottom: 8px;
}

.track-card {
  --tc: var(--primary);
  display: flex;
  flex-direction: column;
  gap: 10px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 22px;
  text-decoration: none;
  position: relative;
  overflow: hidden;
  transition: all 0.2s ease;
}

.track-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--tc);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
  pointer-events: none;
}

.track-card:hover {
  border-color: var(--tc);
  background: var(--bg-card-hover);
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.track-card:hover::before { opacity: 1; }

.track-card-icon { font-size: 26px; }

.track-card-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
}

.track-card-desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.55;
}

/* ── PHASE HEADERS (per-track subsections) ────── */
.phase { margin-bottom: 40px; }

.phase-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 18px;
}

.phase-num {
  font-size: 12px;
  font-weight: 700;
  font-family: 'Fira Code', 'JetBrains Mono', monospace;
  color: var(--primary);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 5px 10px;
  white-space: nowrap;
}

.phase-name {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}

.phase-line {
  flex: 1;
  height: 1px;
  background: var(--border-soft);
}

/* ── COURSE CARDS ──────────────────────────────── */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}

.course-card {
  display: flex;
  flex-direction: column;
  gap: 10px;
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 22px;
  text-decoration: none;
  transition: all 0.2s ease;
  position: relative;
}

.course-card:hover {
  border-color: var(--border);
  background: var(--bg-card-hover);
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.course-card.featured {
  border-color: rgba(56, 189, 248, 0.35);
  background: linear-gradient(160deg, var(--bg-card), var(--bg-elevated));
}

.card-tag {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 11px;
  font-weight: 600;
  color: var(--primary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.card-title {
  font-size: 17px;
  font-weight: 600;
  color: var(--text);
}

.card-desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.6;
}

.featured-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 11px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 20px;
  width: fit-content;
}

.featured-inner {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 24px;
  align-items: center;
}

.btag {
  display: inline-flex;
  align-items: center;
  font-size: 11px;
  font-weight: 700;
  padding: 6px 12px;
  border-radius: 20px;
  text-decoration: none;
  background: var(--primary-soft);
  border: 1px solid rgba(56, 189, 248, 0.3);
  color: var(--primary);
  transition: all 0.18s ease;
}

.btag:hover { background: rgba(56, 189, 248, 0.22); }

/* ── BOOKS SECTION ─────────────────────────────── */
.books-section {
  padding: 64px 24px;
}

.books-inner {
  max-width: 1000px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 44px;
  box-shadow: var(--shadow);
}

.books-eyebrow {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--accent);
  font-family: 'Fira Code', 'JetBrains Mono', monospace;
  margin-bottom: 10px;
}

.books-header { margin-bottom: 32px; }

.books-title {
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.4px;
}

.books-sub {
  margin-top: 8px;
  color: var(--text-secondary);
  font-size: 14px;
}

.books-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.book-card {
  display: flex;
  gap: 18px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 18px;
}

.book-cover {
  flex-shrink: 0;
  width: 84px;
  height: 116px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  padding: 10px;
  text-align: center;
}

.book-cover-hfj { background: linear-gradient(160deg, #38bdf8, #0369a1); }
.book-cover-mja { background: linear-gradient(160deg, var(--accent), #b45309); }

.book-cover-title {
  font-size: 12px;
  font-weight: 700;
  color: #fff;
  line-height: 1.3;
}

.book-info { display: flex; flex-direction: column; gap: 3px; min-width: 0; }

.book-phase {
  font-size: 10px;
  font-weight: 700;
  color: var(--primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.book-name { font-size: 15px; font-weight: 600; }
.book-author { font-size: 12px; color: var(--text-muted); margin-bottom: 4px; }
.book-desc { font-size: 12px; color: var(--text-secondary); line-height: 1.55; }

.book-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }

/* ── FOOTER ─────────────────────────────────────── */
.site-footer {
  max-width: 1180px;
  margin: 40px auto 0;
  padding: 32px 24px 60px;
  border-top: 1px solid var(--border-soft);
  color: var(--text-muted);
  font-size: 13px;
  font-family: 'Fira Code', 'JetBrains Mono', monospace;
  text-align: center;
}

.compile-body .cursor {
  display: inline-block;
  width: 7px;
  height: 14px;
  background: var(--primary);
  animation: blink 1s step-end infinite;
  vertical-align: middle;
}

@keyframes blink { 50% { opacity: 0; } }

.cl { display: block; }
.cl-prompt { color: var(--text); }
.cl-kw { color: var(--primary); }
.cl-cmt { color: var(--text-muted); }
.cl-warn { color: var(--accent); }
.cl-ok { color: var(--success); }

/* ── SCROLL REVEAL (kept from original behavior — JS adds .visible) ─ */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ── RESPONSIVE ─────────────────────────────────── */
@media (max-width: 900px) {
  .books-grid { grid-template-columns: 1fr; }
  .featured-inner { grid-template-columns: 1fr; }
}

@media (max-width: 680px) {
  .hero { padding: 70px 20px 44px; }
  .roadmap-section { padding: 48px 18px 8px; }
  .cards-grid { grid-template-columns: 1fr; }
  .track-overview-grid { grid-template-columns: 1fr; }
  .books-inner { padding: 26px; }
  .book-card { flex-direction: column; }
  .book-cover { width: 100%; height: 90px; }
}

@media (max-width: 400px) {
  .stats-row { gap: 18px; }
  .hero-title { font-size: 32px; }
}