/* ═══════════════════════════════════════════════════════
   LAYOUT.CSS — Header, Nav, Sidebar, Page Grids
═══════════════════════════════════════════════════════ */

/* ── PAGE WRAPPER ─────────────────────────────────── */
#app {
  position: relative; z-index: 1;
  min-height: 100vh;
  display: flex; flex-direction: column;
}

.page-container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
}

/* ── SITE HEADER ──────────────────────────────────── */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(7,9,10,.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.site-header-inner {
  display: flex; align-items: center;
  justify-content: space-between;
  height: 60px;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  gap: var(--gap);
}

/* Logo */
.site-logo {
  display: flex; align-items: center; gap: 10px;
  font-family: var(--font-display);
  font-size: .9rem; font-weight: 900;
  letter-spacing: -.02em;
  color: var(--text-bright);
  white-space: nowrap;
}
.site-logo-mark {
  width: 34px; height: 34px;
  background: linear-gradient(135deg, rgba(61,255,122,.15), rgba(61,255,122,.05));
  border: 1px solid var(--green-dim);
  border-radius: var(--r-sm);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-mono); font-size: .8rem; font-weight: 700;
  color: var(--green); flex-shrink: 0;
}
.site-logo-text span { color: var(--green); }

/* Header Nav */
.header-nav {
  display: flex; align-items: center; gap: 4px;
}
.header-nav-link {
  padding: 6px 14px; border-radius: var(--r-sm);
  font-size: .75rem; font-weight: 500;
  color: var(--text-dim); letter-spacing: .04em;
  transition: all var(--fast) var(--ease);
  white-space: nowrap;
}
.header-nav-link:hover { color: var(--text); background: var(--card); }
.header-nav-link.active { color: var(--text-bright); background: var(--card); }

/* Header Right */
.header-right {
  display: flex; align-items: center; gap: var(--gap-sm);
}
.header-streak {
  display: flex; align-items: center; gap: 5px;
  font-family: var(--font-mono); font-size: .72rem;
  color: var(--text-dim);
  background: var(--card); border: 1px solid var(--border);
  padding: 5px 10px; border-radius: var(--r-sm);
}
.header-streak-val { color: var(--orange); font-weight: 700; }

/* ── MAIN CONTENT AREA ────────────────────────────── */
.page-main {
  flex: 1;
  padding: 32px 24px 64px;
  max-width: 1100px;
  margin: 0 auto;
  width: 100%;
}

/* ── PAGE HERO (topic header) ─────────────────────── */
.page-hero {
  display: flex; align-items: center; gap: var(--gap-lg);
  padding: 28px 32px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--r-xl);
  margin-bottom: 28px;
  position: relative; overflow: hidden;
}
.page-hero::before {
  content: '';
  position: absolute; inset: 0;
  background: radial-gradient(ellipse 60% 100% at 0% 50%, rgba(var(--accent-rgb),.06), transparent);
  pointer-events: none;
}
.page-hero-icon {
  width: 56px; height: 56px; flex-shrink: 0;
  border-radius: var(--r-lg);
  border: 1px solid rgba(var(--accent-rgb),.3);
  background: rgba(var(--accent-rgb),.08);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.6rem;
}
.page-hero-body { flex: 1; min-width: 0; }
.page-hero-title {
  font-family: var(--font-display);
  font-size: 1.2rem; font-weight: 700;
  color: var(--text-bright); margin-bottom: 4px;
}
.page-hero-meta {
  font-size: .75rem; color: var(--text-dim);
  display: flex; gap: var(--gap); flex-wrap: wrap;
}
.page-hero-meta span { display: flex; align-items: center; gap: 4px; }
.page-hero-actions {
  display: flex; gap: var(--gap-sm); flex-wrap: wrap;
}

/* ── SECTION HEADERS ──────────────────────────────── */
.section-head {
  display: flex; align-items: center;
  justify-content: space-between;
  margin-bottom: var(--gap);
  gap: var(--gap-sm); flex-wrap: wrap;
}
.section-label {
  font-size: .62rem; letter-spacing: .14em;
  text-transform: uppercase; font-weight: 700;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

/* ── FILTER BAR ───────────────────────────────────── */
.filter-bar {
  display: flex; align-items: center;
  gap: var(--gap-sm); flex-wrap: wrap;
  padding: 12px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  margin-bottom: 20px;
}
.filter-divider {
  width: 1px; height: 20px;
  background: var(--border);
  flex-shrink: 0;
}
.filter-label {
  font-size: .65rem; color: var(--text-muted);
  letter-spacing: .08em; text-transform: uppercase;
  font-family: var(--font-mono); white-space: nowrap;
}

/* ── STATS ROW ────────────────────────────────────── */
.stats-row {
  display: flex; gap: var(--gap);
  flex-wrap: wrap; margin-bottom: 28px;
}
.stat-card {
  flex: 1; min-width: 110px;
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--r-lg); padding: 14px 18px;
  display: flex; flex-direction: column; align-items: flex-start;
  gap: 4px; transition: border-color var(--fast) var(--ease);
}
.stat-card:hover { border-color: var(--border-2); }
.stat-val {
  font-family: var(--font-display);
  font-size: 1.5rem; font-weight: 700;
  color: var(--text-bright); line-height: 1.1;
}
.stat-label {
  font-size: .65rem; letter-spacing: .08em;
  text-transform: uppercase; color: var(--text-dim);
  font-family: var(--font-mono);
}

/* ── DASHBOARD GRID ───────────────────────────────── */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--gap);
}

/* ── STUDY LAYOUT ─────────────────────────────────── */
.study-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--gap);
}

/* ── TWO COL LAYOUT ───────────────────────────────── */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--gap);
}
@media (max-width: 768px) {
  .two-col { grid-template-columns: 1fr; }
}

/* ── PROGRESS BAR ─────────────────────────────────── */
.pbar {
  background: var(--surface);
  border-radius: 4px; height: 4px; overflow: hidden;
}
.pbar-fill {
  height: 100%; border-radius: 4px;
  background: var(--accent, var(--green));
  transition: width .5s var(--ease);
}
.pbar.thin  { height: 2px; border-radius: 2px; }
.pbar.thick { height: 8px; border-radius: 4px; }

/* ── PROGRESS RING (SVG) ──────────────────────────── */
.progress-ring { position: relative; flex-shrink: 0; }
.progress-ring svg { transform: rotate(-90deg); }
.progress-ring-text {
  position: absolute; inset: 0;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  font-family: var(--font-display);
  font-size: .6rem; font-weight: 700;
  color: var(--text-bright); line-height: 1.1;
}
.progress-ring-text .ring-pct { font-size: .85rem; }

/* ── BACK BUTTON ──────────────────────────────────── */
.back-btn {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: .75rem; color: var(--text-dim);
  padding: 6px 0; margin-bottom: var(--gap-lg);
  transition: color var(--fast);
}
.back-btn:hover { color: var(--text); }
.back-btn::before { content: '←'; }

/* ── BREADCRUMB ───────────────────────────────────── */
.breadcrumb {
  display: flex; align-items: center; gap: 6px;
  font-size: .72rem; color: var(--text-dim);
  margin-bottom: 20px; flex-wrap: wrap;
}
.breadcrumb a:hover { color: var(--text); }
.breadcrumb-sep { color: var(--text-muted); }
.breadcrumb-current { color: var(--text); }

/* ── RESPONSIVE ───────────────────────────────────── */
@media (max-width: 768px) {
  .page-main { padding: 20px 16px 48px; }
  .page-hero  { padding: 20px; flex-wrap: wrap; }
  .stats-row  { gap: var(--gap-sm); }
  .stat-card  { min-width: 90px; padding: 12px 14px; }
  .site-header-inner { padding: 0 16px; }
}
@media (max-width: 480px) {
  .page-container { padding: 0 14px; }
  .topic-grid { grid-template-columns: 1fr; }
  .header-nav { display: none; }
}

/* ── ALIASES (used by HTML pages) ─────────────────── */
.header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(7,9,10,.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex; align-items: center;
  justify-content: space-between;
  height: 60px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  gap: var(--gap);
}
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px var(--gap-xl);
  width: 100%;
}
.header-logo {
  display: flex; align-items: center; gap: 8px;
  font-family: var(--font-display);
  font-size: .88rem; font-weight: 900;
  color: var(--text-bright);
  letter-spacing: -.01em;
  white-space: nowrap;
  text-decoration: none;
}
.header-logo-icon {
  font-size: 1.1rem;
}
.header-logo strong { color: var(--green); }
.header-stats {
  display: flex; align-items: center; gap: 12px;
}
.header-stat {
  display: flex; align-items: center; gap: 5px;
  font-family: var(--font-mono); font-size: .72rem;
  color: var(--text-dim);
}
.header-stat-icon { font-size: .85rem; }
@media (max-width: 600px) {
  .header-inner { padding: 0 14px; }
  .container    { padding: 0 14px var(--gap-xl); }
  .header-nav   { display: none; }
  .header-stats { gap: 8px; }
}