*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: #f0f2f5;
  color: #1a1a2e;
}

.layout {
  display: flex;
  min-height: 100vh;
}

/* ── Sidebar ─────────────────────────────────────────────── */

#sidebar {
  width: 230px;
  min-width: 230px;
  background: #141929;
  position: fixed;
  top: 0;
  left: 0;
  height: 100vh;
  overflow-y: auto;
  padding-bottom: 2rem;
  border-right: 1px solid #1e2540;
}

#sidebar::-webkit-scrollbar { width: 4px; }
#sidebar::-webkit-scrollbar-thumb { background: #2e3857; border-radius: 2px; }

.nav-header {
  padding: 1.5rem 1.25rem 1.1rem;
  border-bottom: 1px solid #1e2540;
  margin-bottom: 0.5rem;
}

.nav-site-title {
  display: block;
  color: #fff;
  font-weight: 700;
  font-size: 0.95rem;
  text-decoration: none;
  letter-spacing: 0.01em;
  margin-bottom: 0.25rem;
}

.nav-site-title:hover { color: #7ba7f7; }

.nav-site-sub {
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #4a5275;
}

.nav-group {
  margin-bottom: 0.25rem;
}

.nav-group-label {
  padding: 0.75rem 1.25rem 0.25rem;
  font-size: 0.62rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: #4a5275;
  font-weight: 700;
}

.nav-link {
  display: block;
  padding: 0.38rem 1.25rem;
  color: #8892b0;
  text-decoration: none;
  font-size: 0.83rem;
  transition: color 0.12s, background 0.12s;
  border-left: 3px solid transparent;
}

.nav-link:hover {
  color: #ccd6f6;
  background: #1e2540;
}

.nav-link.active {
  color: #e6f1ff;
  background: #1e2540;
  border-left-color: #4f8ef7;
}

/* ── Main Content ────────────────────────────────────────── */

.content {
  margin-left: 230px;
  padding: 2.5rem 3rem 4rem;
  flex: 1;
  min-width: 0;
}

.content h1 {
  font-size: 1.5rem;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 0.4rem;
}

.page-subtitle {
  font-size: 0.88rem;
  color: #64748b;
  margin-bottom: 2.25rem;
  padding-bottom: 1.25rem;
  border-bottom: 2px solid #e2e8f0;
}

/* ── Code Sections ───────────────────────────────────────── */

.code-section {
  margin-bottom: 2.5rem;
}

.section-label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  font-weight: 700;
  color: #64748b;
  margin-bottom: 0.6rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid #e2e8f0;
}

.code-section pre {
  border-radius: 8px;
  overflow-x: auto;
  font-size: 0.8rem;
  line-height: 1.6;
  box-shadow: 0 2px 8px rgba(0,0,0,0.12);
}

.code-section code {
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
}

/* ── Day Schedule ────────────────────────────────────────── */

.day-schedule {
  margin-bottom: 2.5rem;
  padding-bottom: 2rem;
  border-bottom: 2px solid #e2e8f0;
}

.schedule-heading {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  font-weight: 700;
  color: #64748b;
  margin-bottom: 0.6rem;
  margin-top: 1.5rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid #e2e8f0;
}

.day-schedule .schedule-heading:first-child {
  margin-top: 0;
}

.schedule-columns {
  display: flex;
  gap: 2rem;
  flex-wrap: wrap;
}

.schedule-col {
  flex: 1;
  min-width: 260px;
}

.schedule-col-label {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #4f8ef7;
  margin-bottom: 0.45rem;
}

.schedule-table {
  width: 100%;
  border-collapse: collapse;
}

.schedule-table th {
  text-align: left;
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #94a3b8;
  padding: 0.3rem 0.75rem;
  border-bottom: 1px solid #e2e8f0;
}

.schedule-table td {
  padding: 0.45rem 0.75rem;
  vertical-align: top;
  border-bottom: 1px solid #f1f5f9;
}

.schedule-time {
  white-space: nowrap;
  color: #64748b;
  font-variant-numeric: tabular-nums;
  width: 72px;
  font-size: 0.82rem;
}

.schedule-activity {
  font-weight: 600;
  color: #1e293b;
  font-size: 0.87rem;
}

.schedule-notes {
  font-weight: 400;
  color: #64748b;
  font-size: 0.8rem;
  margin-top: 0.1rem;
}

.schedule-minor td {
  color: #94a3b8;
  font-style: italic;
  font-weight: 400;
}

.objectives-list {
  padding-left: 1.4rem;
  color: #334155;
  font-size: 0.88rem;
  line-height: 1.9;
  max-width: 680px;
}

/* ── Index Page ──────────────────────────────────────────── */

.index-intro {
  max-width: 640px;
  margin-bottom: 2.5rem;
  line-height: 1.7;
  color: #334155;
  font-size: 0.95rem;
}

.group-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.25rem;
  max-width: 860px;
}

.group-card {
  background: #fff;
  border-radius: 10px;
  padding: 1.5rem 1.75rem;
  box-shadow: 0 1px 4px rgba(0,0,0,0.08);
  border: 1px solid #e2e8f0;
}

.group-card h2 {
  font-size: 1rem;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 0.9rem;
}

.group-card a {
  display: block;
  font-size: 0.85rem;
  color: #3b82f6;
  text-decoration: none;
  padding: 0.22rem 0;
}

.group-card a:hover { text-decoration: underline; }