/* ================================================================
   assets/css/dsa-chapter.css
   Shared styles for DSA chapter editorial pages
   Loaded via  custom_css: dsa-chapter  in front matter
   ================================================================ */

:root {
  --ch-1: #00c9a7;
  --ch-2: #00b4d8;
  --ch-grad: linear-gradient(135deg, var(--ch-1), var(--ch-2));
}

/* ── Chapter hero ─────────────────────────────────────────────── */
.chapter-hero {
  background: linear-gradient(135deg, #0a1f1c 0%, #0d2d2a 50%, #0a1a2e 100%);
  color: white;
  padding: 2.5rem 2rem 2rem;
  border-radius: 16px;
  margin-bottom: 2rem;
  position: relative;
  overflow: hidden;
}
.chapter-hero::before {
  content: '';
  position: absolute; inset: 0;
  background: radial-gradient(ellipse at 75% 25%, rgba(0,201,167,.15) 0%, transparent 55%),
              radial-gradient(ellipse at 15% 75%, rgba(0,180,216,.12) 0%, transparent 50%);
  pointer-events: none;
}
.chapter-hero-inner { position: relative; }
.ch-hero-breadcrumb {
  font-size: 0.8rem; color: rgba(255,255,255,.55);
  margin-bottom: 1rem; display: flex; align-items: center; gap: 0.4rem;
}
.ch-hero-breadcrumb a { color: var(--ch-1); text-decoration: none; }
.chapter-num-badge {
  display: inline-block;
  padding: 0.25rem 0.8rem;
  background: rgba(0,201,167,.2);
  border: 1px solid rgba(0,201,167,.4);
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--ch-1);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.75rem;
}
.chapter-hero h1 {
  font-size: 2rem;
  font-weight: 900;
  margin: 0 0 0.6rem;
  background: var(--ch-grad);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
}
.chapter-hero-sub {
  color: rgba(255,255,255,.65);
  font-size: 0.95rem;
  margin: 0 0 1.25rem;
  line-height: 1.7;
}
.chapter-meta-row {
  display: flex; flex-wrap: wrap; gap: 0.6rem; align-items: center;
}
.ch-meta-pill {
  padding: 0.2rem 0.65rem;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 700;
  background: rgba(255,255,255,.08);
  color: rgba(255,255,255,.75);
  border: 1px solid rgba(255,255,255,.12);
}
.ch-meta-pill.teal { background: rgba(0,201,167,.15); color: var(--ch-1); border-color: rgba(0,201,167,.3); }
.ch-nav-btn {
  display: inline-flex; align-items: center; gap: 0.3rem;
  padding: 0.35rem 0.9rem;
  border-radius: 8px;
  font-size: 0.8rem; font-weight: 700;
  text-decoration: none;
  background: rgba(0,201,167,.15);
  border: 1px solid rgba(0,201,167,.35);
  color: var(--ch-1);
  transition: opacity .15s;
}
.ch-nav-btn:hover { opacity: 0.8; }

/* ── Section layout ───────────────────────────────────────────── */
.chapter-content { max-width: 860px; margin: 0 auto; }
.chapter-content.has-sidebar { max-width: 1100px; display: flex; gap: 2.5rem; align-items: flex-start; }

.chapter-sidebar { width: 260px; flex-shrink: 0; }
.sidebar-sticky {
  position: sticky; top: 90px;
  background: var(--bg-color, #fff); border: 1px solid var(--border-color, #eee);
  border-radius: 12px; padding: 1.25rem;
}
.sidebar-title {
  font-size: 0.95rem; font-weight: 800; margin: 0 0 1rem;
  color: var(--text-color); padding-bottom: 0.5rem; border-bottom: 1px solid var(--border-color, #eee);
}
.chapter-sidebar .toc-nav ul { list-style: none !important; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 0.3rem; }
.chapter-sidebar .toc-nav li { padding: 0; margin: 0; list-style-type: none !important; }
.chapter-sidebar .toc-nav a {
  text-decoration: none !important; color: var(--text-color) !important; font-size: 0.85rem; line-height: 1.4;
  display: block; padding: 0.4rem 0.6rem; border-radius: 6px; transition: all 0.2s ease;
}
.chapter-sidebar .toc-nav a:hover {
  background: rgba(0,201,167,.15) !important; color: var(--ch-1) !important; font-weight: 600;
}
.chapter-main { flex: 1; min-width: 0; }

@media (max-width: 800px) {
  .chapter-content.has-sidebar { flex-direction: column; }
  .chapter-sidebar { width: 100%; border-bottom: 1px solid var(--border-color, #eee); padding-bottom: 1.5rem; margin-bottom: 1rem; }
  .sidebar-sticky { position: static; border: none; padding: 0; background: transparent; }
}

.chapter-section {
  margin-bottom: 2.5rem;
  padding-bottom: 2.5rem;
  border-bottom: 1px solid var(--border-color);
}
.chapter-section:last-child { border-bottom: none; }

.section-heading {
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--text-color);
  margin: 0 0 0.75rem;
  padding-left: 0.75rem;
  border-left: 3px solid var(--ch-1);
}
.section-subheading {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-color);
  margin: 1.25rem 0 0.5rem;
}
.chapter-section p {
  font-size: 0.9rem;
  color: var(--text-color);
  line-height: 1.75;
  margin: 0 0 0.75rem;
}

/* Insight / key insight box */
.insight-box {
  background: rgba(0,201,167,.06);
  border: 1px solid rgba(0,201,167,.2);
  border-radius: 8px;
  padding: 0.85rem 1rem;
  margin: 0.75rem 0;
  font-size: 0.87rem;
  line-height: 1.65;
  color: var(--text-color);
}
.insight-box strong { color: var(--ch-1); }
.insight-box ul { margin: 0.4rem 0 0; padding-left: 1.2rem; }
.insight-box li { margin-bottom: 0.2rem; }
.insight-label {
  font-size: 0.7rem; font-weight: 800;
  text-transform: uppercase; letter-spacing: 0.06em;
  color: var(--ch-1); margin-bottom: 0.4rem; display: block;
}

/* Complexity row in editorial */
.ch-cplx-row { display: flex; gap: 0.5rem; flex-wrap: wrap; margin: 0.5rem 0 0.75rem; }
.ch-cplx {
  padding: 0.2rem 0.65rem;
  background: rgba(0,201,167,.1);
  border: 1px solid rgba(0,201,167,.2);
  border-radius: 6px;
  font-size: 0.78rem; font-weight: 700;
  color: var(--ch-1); font-family: monospace;
}
.ch-cplx span { font-weight: 400; color: var(--light-text); font-family: inherit; font-size: 0.72rem; margin-right: 0.2rem; }

/* Code block in editorial */
.ch-code-wrap { margin: 0.75rem 0 1rem; }
.ch-code-label {
  font-size: 0.7rem; font-weight: 800; text-transform: uppercase;
  letter-spacing: 0.05em; color: var(--light-text);
  margin-bottom: 0.3rem; display: block;
}
.ch-code-wrap pre {
  margin: 0; border-radius: 8px;
  background: var(--card-bg); border: 1px solid var(--border-color);
  overflow-x: auto;
}

/* Pattern summary in editorial */
.pattern-summary {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 0.65rem; margin: 0.75rem 0;
}
.pattern-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.7rem 0.85rem;
}
.pattern-card h4 { font-size: 0.82rem; font-weight: 800; color: var(--ch-1); margin: 0 0 0.3rem; }
.pattern-card p { font-size: 0.78rem; color: var(--light-text); margin: 0; line-height: 1.5; }

/* Problems in editorial */
.ch-ed-problems { margin-top: 0.5rem; }
.ch-ed-problems table { width: 100%; border-collapse: collapse; font-size: 0.84rem; }
.ch-ed-problems th {
  text-align: left; padding: 0.4rem 0.6rem;
  border-bottom: 2px solid var(--border-color);
  font-size: 0.72rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.04em; color: var(--light-text); background: var(--bg-color);
}
.ch-ed-problems td { padding: 0.4rem 0.6rem; border-bottom: 1px solid var(--border-color); vertical-align: middle; }
.ch-ed-problems tr:last-child td { border-bottom: none; }
.ch-ed-problems tr:hover td { background: var(--bg-color); }
.ch-ed-problems a { color: var(--text-color); text-decoration: none; }
.ch-ed-problems a:hover { color: var(--ch-1); }

/* Next/Prev nav */
.chapter-nav-footer {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: 2.5rem; padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
  flex-wrap: wrap; gap: 0.75rem;
}
.ch-nav-footer-btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  border-radius: 8px;
  font-size: 0.85rem; font-weight: 700; text-decoration: none;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  color: var(--text-color);
  transition: border-color .15s, color .15s;
}
.ch-nav-footer-btn:hover { border-color: var(--ch-1); color: var(--ch-1); }
.ch-nav-footer-btn.primary { background: var(--ch-grad); color: #fff; border-color: transparent; }

/* ── Insight Table ─────────────────────────────────────────────── */
/* Responsive wrapper — enables horizontal scroll on small screens */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: 10px;
  border: 1px solid var(--border-color, #e5e7eb);
  margin: 0.85rem 0 1.25rem;
  box-shadow: 0 1px 4px rgba(0,0,0,.06);
}

/* The table itself */
.insight-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  line-height: 1.5;
  background: var(--card-bg, #fff);
  min-width: 480px; /* stops columns collapsing on narrow viewports */
}

/* Header row */
.insight-table thead tr {
  background: linear-gradient(90deg, rgba(0,201,167,.12), rgba(0,180,216,.08));
  border-bottom: 2px solid rgba(0,201,167,.25);
}

.insight-table th {
  padding: 0.6rem 1rem;
  text-align: left;
  font-size: 0.75rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.055em;
  color: var(--ch-1, #00c9a7);
  white-space: nowrap;
}

/* Body cells */
.insight-table td {
  padding: 0.55rem 1rem;
  border-bottom: 1px solid var(--border-color, #e5e7eb);
  color: var(--text-color);
  vertical-align: middle;
}

/* Last row — no bottom border */
.insight-table tbody tr:last-child td {
  border-bottom: none;
}

/* Zebra stripe */
.insight-table tbody tr:nth-child(even) {
  background: rgba(0,201,167,.03);
}

/* Hover highlight */
.insight-table tbody tr:hover {
  background: rgba(0,201,167,.07);
  transition: background 0.15s ease;
}

/* Strong text inside table inherits teal accent */
.insight-table td strong {
  color: var(--ch-1, #00c9a7);
}

/* ── Difficulty badges ─────────────────────────────────────────── */
/* Used in Top 50 problems tables and chapter hero stats */
.diff-easy {
  display: inline-block;
  padding: 0.18rem 0.55rem;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: rgba(22,163,74,.12);
  color: #16a34a;
  border: 1px solid rgba(22,163,74,.25);
}
.diff-medium {
  display: inline-block;
  padding: 0.18rem 0.55rem;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: rgba(234,179,8,.12);
  color: #b45309;
  border: 1px solid rgba(234,179,8,.3);
}
.diff-hard {
  display: inline-block;
  padding: 0.18rem 0.55rem;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: rgba(220,38,38,.1);
  color: #dc2626;
  border: 1px solid rgba(220,38,38,.25);
}
.diff-intermediate {
  display: inline-block;
  padding: 0.18rem 0.55rem;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  background: rgba(124,58,237,.1);
  color: #7c3aed;
  border: 1px solid rgba(124,58,237,.25);
}

/* ── hero stats badges (ch-subtitle area) ─────────────────────── */
.hero-stats {
  display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 0.75rem;
}
.stat-badge {
  display: inline-flex; align-items: center; gap: 0.3rem;
  padding: 0.25rem 0.7rem;
  border-radius: 20px;
  font-size: 0.75rem; font-weight: 700;
  background: rgba(255,255,255,.1);
  color: rgba(255,255,255,.85);
  border: 1px solid rgba(255,255,255,.18);
}
.stat-badge .icon { font-size: 0.82rem; }
/* Override difficulty colours in the dark hero context */
.chapter-hero .diff-hard {
  background: rgba(220,38,38,.2);
  color: #fca5a5;
  border-color: rgba(220,38,38,.35);
}
.chapter-hero .diff-intermediate {
  background: rgba(124,58,237,.2);
  color: #c4b5fd;
  border-color: rgba(124,58,237,.35);
}

/* ── Breadcrumb inside hero ────────────────────────────────────── */
.breadcrumb {
  font-size: 0.78rem;
  color: rgba(255,255,255,.5);
  margin-bottom: 0.6rem;
  display: flex; align-items: center; gap: 0.35rem;
}
.breadcrumb a { color: var(--ch-1, #00c9a7); text-decoration: none; }
.breadcrumb .separator { opacity: 0.45; }
.breadcrumb .current { color: rgba(255,255,255,.75); }

/* ── Chapter sub-title ─────────────────────────────────────────── */
.ch-subtitle {
  color: rgba(255,255,255,.6);
  font-size: 0.9rem;
  margin: 0.25rem 0 0;
  line-height: 1.6;
}

/* ── Responsive ───────────────────────────────────────────────── */
@media (max-width: 640px) {
  .chapter-hero h1 { font-size: 1.6rem; }
  .pattern-summary { grid-template-columns: 1fr; }
  .insight-table { font-size: 0.8rem; }
  .insight-table th, .insight-table td { padding: 0.45rem 0.65rem; }
}