/* ════════════════════════════════════════════════════════════════
   TeqStudy — Course Template (High Voltage design system)
   Shared stylesheet for the standard course page pattern:
   header + sidebar nav + progress bar + lesson/card/callout/quiz.
   Pages migrate onto this one file instead of each keeping their
   own copy — see css/index.css for the same system on the homepage.
   ════════════════════════════════════════════════════════════════ */

:root {
  --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;
  --success-soft: rgba(52, 211, 153, 0.15);
  --danger: #f87171;
  --danger-soft: rgba(248, 113, 113, 0.12);
  --purple: #a78bfa;
  --purple-soft: rgba(167, 139, 250, 0.15);
  --radius: 16px;
  --radius-sm: 12px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);

  /* legacy names some pages/inline styles still reference */
  --surface: var(--bg-elevated);
  --card: var(--bg-card);
  --code-bg: #0d1420;
  --muted: var(--text-muted);
  --accent1: var(--danger);
  --accent2: var(--accent);
  --accent3: var(--success);
  --accent4: var(--primary);
  --accent5: var(--purple);
}

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

body {
  font-family: 'Inter', 'Nunito', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(56, 189, 248, 0.10), transparent),
    radial-gradient(ellipse 60% 40% at 85% 15%, rgba(251, 191, 36, 0.05), transparent);
  background-attachment: fixed;
}

/* ── HEADER ───────────────────────────────────── */
header {
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border-soft);
  padding: 56px 40px 68px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
header::before {
  content: '';
  position: absolute; inset: 0;
  background: radial-gradient(circle at 30% 40%, rgba(56, 189, 248, 0.10) 0%, transparent 55%),
              radial-gradient(circle at 75% 60%, rgba(251, 191, 36, 0.06) 0%, transparent 50%);
  pointer-events: none; /* decorative only — never intercept clicks on header content */
}
.header-badge {
  display: inline-block;
  background: var(--primary-soft);
  border: 1px solid rgba(56, 189, 248, 0.3);
  color: var(--primary);
  font-weight: 600;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 6px 16px;
  border-radius: 20px;
  margin-bottom: 20px;
}
header h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 700;
  letter-spacing: -0.5px;
  background: linear-gradient(135deg, var(--text) 30%, var(--primary) 75%, var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.15;
  margin-bottom: 14px;
}
header p {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 28px;
}
.header-stars { font-size: 1.4rem; letter-spacing: 6px; opacity: 0.7; }

/* header-actions links (course-to-course nav) */
.header-actions { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.header-actions a {
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 9px 16px;
  color: var(--text);
  background: var(--bg-card);
  font-weight: 600;
  font-size: 13px;
  transition: all 0.18s ease;
}
.header-actions a:hover { border-color: var(--primary); transform: translateY(-1px); }

/* ── PROGRESS BAR ─────────────────────────────── */
.progress-bar-wrap {
  background: rgba(11, 15, 26, 0.85);
  backdrop-filter: blur(12px);
  padding: 12px 40px;
  display: flex;
  align-items: center;
  gap: 16px;
  border-bottom: 1px solid var(--border-soft);
  position: sticky;
  top: 0;
  z-index: 100;
}
.progress-label { font-size: 12px; font-weight: 600; color: var(--text-muted); white-space: nowrap; }
.progress-track {
  flex: 1;
  height: 6px;
  background: var(--bg-card);
  border-radius: 3px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), #0ea5e9);
  border-radius: 3px;
  transition: width 0.5s ease;
  width: 0%;
}
.progress-pct { font-size: 12px; font-weight: 700; color: var(--primary); }

/* streak bar (module-progress dots — CLion & similar) */
.streak-bar { display: flex; align-items: center; gap: 6px; padding: 12px 20px 18px; border-bottom: 1px solid var(--border-soft); }
.streak-label { font-size: 10px; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-muted); margin-right: 4px; }
.streak-node { width: 9px; height: 9px; border-radius: 50%; background: var(--border); border: 2px solid var(--border); transition: all 0.3s ease; flex-shrink: 0; }
.streak-node.done { background: var(--accent); border-color: var(--accent); box-shadow: 0 0 8px rgba(251, 191, 36, 0.5); }
.streak-node.current { background: transparent; border-color: var(--accent); animation: pulse-node 1.5s ease-in-out infinite; }
@keyframes pulse-node { 0%, 100% { box-shadow: 0 0 0 0 rgba(251, 191, 36, 0.4); } 50% { box-shadow: 0 0 0 5px rgba(251, 191, 36, 0); } }

/* ── LAYOUT ───────────────────────────────────── */
.layout { display: flex; max-width: 1200px; margin: 0 auto; gap: 0; }

/* ── SIDEBAR ──────────────────────────────────── */
.sidebar {
  width: 264px;
  flex-shrink: 0;
  padding: 28px 18px;
  position: sticky;
  top: 49px;
  height: calc(100vh - 49px);
  overflow-y: auto;
  border-right: 1px solid var(--border-soft);
}
.sidebar-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 14px;
  padding-left: 8px;
}
.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.18s ease;
  margin-bottom: 3px;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
}
.nav-item:hover { background: rgba(255,255,255,0.04); color: var(--text); }
.nav-item.active {
  background: linear-gradient(90deg, rgba(56, 189, 248, 0.16), rgba(56, 189, 248, 0.04));
  color: var(--primary);
  box-shadow: inset 3px 0 0 var(--primary);
}
.nav-item .nav-icon { font-size: 17px; flex-shrink: 0; }
.nav-item .nav-check { margin-left: auto; font-size: 13px; color: var(--success); }

/* ── MAIN CONTENT ─────────────────────────────── */
.main { flex: 1; padding: 36px 46px; min-width: 0; }

/* ── LESSON SECTION ───────────────────────────── */
.lesson { display: none; animation: fadeIn 0.4s ease; }
.lesson.active { display: block; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }

.lesson-header { margin-bottom: 32px; }
.lesson-num {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 8px;
}
.lesson h2 { font-size: clamp(1.6rem, 3vw, 2.3rem); font-weight: 700; letter-spacing: -0.4px; line-height: 1.2; margin-bottom: 12px; }
.lesson-intro {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 680px;
  border-left: 3px solid var(--primary);
  padding-left: 16px;
}

/* ── CARDS ────────────────────────────────────── */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 26px;
  margin-bottom: 24px;
}
.card-title { font-size: 1.15rem; font-weight: 600; margin-bottom: 14px; display: flex; align-items: center; gap: 10px; }
.card p, .card li { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: 10px; }
.card ul, .card ol { padding-left: 20px; }
.card li { margin-bottom: 6px; }

/* ── CALLOUT BOXES ────────────────────────────── */
.callout {
  border-radius: var(--radius-sm);
  padding: 18px 22px;
  margin: 18px 0;
  display: flex;
  gap: 14px;
  align-items: flex-start;
}
.callout-emoji { font-size: 1.4rem; flex-shrink: 0; margin-top: 2px; }
.callout-body { font-size: 0.93rem; color: var(--text-secondary); }
.callout-body strong { display: block; font-size: 0.98rem; margin-bottom: 4px; color: var(--text); }
.callout.tip { background: var(--success-soft); border: 1px solid rgba(52, 211, 153, 0.3); }
.callout.tip .callout-body strong { color: var(--success); }
.callout.warn { background: var(--accent-soft); border: 1px solid rgba(251, 191, 36, 0.3); }
.callout.warn .callout-body strong { color: var(--accent); }
.callout.fun { background: var(--purple-soft); border: 1px solid rgba(167, 139, 250, 0.3); }
.callout.fun .callout-body strong { color: var(--purple); }
.callout.info { background: var(--primary-soft); border: 1px solid rgba(56, 189, 248, 0.3); }
.callout.info .callout-body strong { color: var(--primary); }

/* ── CODE BLOCKS ──────────────────────────────── */
.code-block {
  background: var(--code-bg);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  margin: 18px 0;
  overflow: hidden;
}
.code-header {
  background: var(--bg-elevated);
  padding: 10px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-soft);
}
.code-lang { font-size: 11px; font-weight: 700; color: var(--primary); letter-spacing: 0.06em; text-transform: uppercase; }
.code-dots { display: flex; gap: 6px; }
.code-dots span { width: 10px; height: 10px; border-radius: 50%; }
.code-dots span:nth-child(1) { background: #f87171; }
.code-dots span:nth-child(2) { background: var(--accent); }
.code-dots span:nth-child(3) { background: var(--success); }
pre { padding: 20px 22px; overflow-x: auto; font-family: 'Fira Code', monospace; font-size: 0.86rem; line-height: 1.8; }

/* Syntax colors */
.kw { color: var(--purple); font-weight: 500; }
.cl { color: var(--accent); }
.fn { color: var(--success); }
.str { color: #fb923c; }
.cm { color: var(--text-muted); font-style: italic; }
.num { color: #f472b6; }
.var { color: var(--text); }
.cls { color: var(--accent); }
.bi { color: var(--primary); }
.out { color: #a7f3d0; }
.dec { color: var(--danger); }

/* ── QUIZ ─────────────────────────────────────── */
.quiz-block {
  background: linear-gradient(160deg, var(--bg-card), var(--bg-elevated));
  border: 1px solid rgba(56, 189, 248, 0.3);
  border-radius: var(--radius);
  padding: 26px;
  margin: 26px 0;
}
.quiz-title { font-size: 1.1rem; font-weight: 700; color: var(--primary); margin-bottom: 14px; display: flex; align-items: center; gap: 8px; }
.quiz-q { font-size: 0.98rem; font-weight: 600; margin-bottom: 16px; }
.quiz-options { display: flex; flex-direction: column; gap: 10px; }
.quiz-option {
  background: var(--bg-card);
  border: 2px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 12px 18px;
  cursor: pointer;
  font-size: 0.93rem;
  font-weight: 500;
  transition: all 0.18s ease;
  text-align: left;
  color: var(--text);
}
.quiz-option:hover { border-color: var(--primary); background: var(--primary-soft); }
.quiz-option.correct { border-color: var(--success); background: var(--success-soft); color: var(--success); }
.quiz-option.wrong { border-color: var(--danger); background: var(--danger-soft); color: var(--danger); }
.quiz-feedback { margin-top: 14px; padding: 12px 16px; border-radius: var(--radius-sm); font-weight: 600; font-size: 0.93rem; display: none; }
.quiz-feedback.show { display: block; }
.quiz-feedback.ok { background: var(--success-soft); color: var(--success); border: 1px solid rgba(52, 211, 153, 0.3); }
.quiz-feedback.bad { background: var(--danger-soft); color: var(--danger); border: 1px solid rgba(248, 113, 113, 0.3); }

/* ── ANALOGY / CHALLENGE BOXES ────────────────── */
.analogy {
  background: linear-gradient(135deg, var(--accent-soft), rgba(248, 113, 113, 0.05));
  border: 1px solid rgba(251, 191, 36, 0.25);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  margin: 18px 0;
}
.analogy-label { font-size: 11px; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; color: var(--accent); margin-bottom: 8px; }
.analogy p { font-size: 0.95rem; color: var(--text-secondary); }

.challenge {
  background: linear-gradient(135deg, var(--primary-soft), var(--success-soft));
  border: 1px solid rgba(56, 189, 248, 0.3);
  border-radius: var(--radius-sm);
  padding: 22px 26px;
  margin: 22px 0;
}
.challenge-label { font-size: 11px; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; color: var(--primary); margin-bottom: 8px; }
.challenge h4 { font-size: 1.02rem; margin-bottom: 10px; }
.challenge p, .challenge li { font-size: 0.93rem; color: var(--text-secondary); }

/* ── INSIGHT ROW (CLion & similar) ─────────────── */
.insight-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 14px; margin: 20px 0; }
.insight-card {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 18px;
  border-top: 2px solid var(--accent);
  transition: transform 0.2s ease;
}
.insight-card:hover { transform: translateY(-3px); }
.insight-card .ic-icon { font-size: 1.5rem; margin-bottom: 10px; }
.insight-card h5 { font-size: 0.93rem; font-weight: 700; margin-bottom: 6px; color: var(--accent); }
.insight-card p { font-size: 0.82rem; color: var(--text-muted); line-height: 1.6; }

/* ── STEP LIST (numbered walkthroughs) ─────────── */
.step-list { counter-reset: step; list-style: none; padding: 0; }
.step-list li {
  counter-increment: step;
  display: flex; gap: 14px;
  padding: 13px 0; border-bottom: 1px solid var(--border-soft);
  font-size: 0.93rem; color: var(--text-secondary);
}
.step-list li::before {
  content: counter(step);
  display: flex; align-items: center; justify-content: center;
  width: 25px; height: 25px;
  background: linear-gradient(135deg, var(--primary), #0ea5e9);
  color: #0b0f1a; font-weight: 700; font-size: 12px;
  border-radius: 50%; flex-shrink: 0; margin-top: 2px;
}

/* ── NAV BUTTONS ──────────────────────────────── */
.lesson-nav { display: flex; justify-content: space-between; margin-top: 46px; padding-top: 26px; border-top: 1px solid var(--border-soft); }
.btn { padding: 11px 26px; border-radius: 10px; font-family: inherit; font-size: 0.92rem; font-weight: 600; cursor: pointer; border: none; transition: all 0.2s ease; }
.btn-next { background: linear-gradient(135deg, var(--primary), #0ea5e9); color: #0b0f1a; }
.btn-next:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(56, 189, 248, 0.3); }
.btn-prev { background: var(--bg-card); color: var(--text-secondary); border: 1px solid var(--border-soft); }
.btn-prev:hover { color: var(--text); border-color: var(--primary); }
.btn:disabled { opacity: 0.3; cursor: not-allowed; transform: none !important; box-shadow: none !important; }
.next.btn, button.next { background: linear-gradient(135deg, var(--primary), #0ea5e9); color: #0b0f1a; }

/* ── SECTION DIVIDER ──────────────────────────── */
.section-divider { display: flex; align-items: center; gap: 14px; margin: 26px 0; }
.section-divider span { font-size: 11px; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-muted); white-space: nowrap; }
.section-divider::before, .section-divider::after { content: ''; flex: 1; height: 1px; background: var(--border-soft); }

/* ── TABLE (mobile-scroll-safe from the start) ─── */
table { width: 100%; border-collapse: collapse; font-size: 0.9rem; margin: 16px 0; }
th { background: var(--bg-elevated); color: var(--primary); font-weight: 700; padding: 11px 15px; text-align: left; border-bottom: 2px solid var(--border-soft); }
td { padding: 10px 15px; border-bottom: 1px solid var(--border-soft); color: var(--text-secondary); }
tr:hover td { background: rgba(255,255,255,0.02); }

/* ── BADGE ────────────────────────────────────── */
.badge { display: inline-block; padding: 3px 10px; border-radius: 20px; font-size: 11px; font-weight: 700; letter-spacing: 0.02em; }
.badge-green { background: var(--success-soft); color: var(--success); }
.badge-purple { background: var(--purple-soft); color: var(--purple); }
.badge-yellow { background: var(--accent-soft); color: var(--accent); }
.badge-red { background: var(--danger-soft); color: var(--danger); }

/* ── PILLAR CARDS ─────────────────────────────── */
.pillars { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; margin: 22px 0; }
.pillar-card {
  background: var(--bg-card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 20px;
  text-align: center;
  transition: transform 0.2s ease;
}
.pillar-card:hover { transform: translateY(-4px); }
.pillar-icon { font-size: 2.2rem; margin-bottom: 12px; }
.pillar-card h4 { font-size: 1.02rem; font-weight: 700; margin-bottom: 8px; }
.pillar-card p { font-size: 0.85rem; color: var(--text-muted); }

/* ── SCROLLBAR ────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ── MOBILE (baked in — see the earlier session's
   mobile-fixes.css lessons: sidebar collapse, table
   scroll, grid min-width, header::before pointer-events
   already handled above from the start) ─────────── */
@media (max-width: 768px) {
  .sidebar { display: none !important; width: 100% !important; position: static !important; height: auto !important; }
  .layout { display: block !important; }
  .main { width: 100% !important; padding: 24px 18px !important; }
  .progress-bar-wrap { padding: 10px 18px; flex-wrap: wrap; }
  header { padding: 40px 20px 56px; }

  table {
    display: block;
    max-width: 100%;
    overflow-x: auto !important;
    -webkit-overflow-scrolling: touch;
    white-space: nowrap;
  }
  table code { overflow-wrap: anywhere; word-break: break-word; }

  .insight-row, .pillars, .objectives, .notes { grid-template-columns: 1fr !important; }
  .compare-grid, .compare-col, .two-col { grid-template-columns: 1fr !important; min-width: 0; }

  button, .nav-btn, .btn { min-height: 44px !important; padding: 12px !important; }
}

html, body { overflow-x: hidden; }