/* ============================================
   layout.css — topbar, sidebar, content grid
   ============================================ */

/* ---------- Topbar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--c-topbar-bg, rgba(255,255,255,0.78));
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--c-border);
  height: var(--topbar-h);
}

.topbar-inner {
  height: 100%;
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.menu-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  width: 38px; height: 38px;
  font-size: 1.2rem;
  color: var(--c-text);
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 0.55rem;
  color: var(--c-text);
  font-weight: 700;
  position: relative;
  padding-left: 0.9rem;
}
/* small green tick mark before the brand — a quiet logo cue */
.brand::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 5px;
  height: 1.3rem;
  border-radius: 3px;
  background: var(--grad);
}
.brand:hover { text-decoration: none; }
.brand-mark {
  color: var(--c-text);
  font-size: 1.08rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.brand-sub {
  color: var(--c-muted);
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: -0.01em;
}

.topbar-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.topbar-link {
  color: var(--c-text-soft);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.4rem 0.7rem;
  border-radius: var(--radius-sm);
  transition: color 0.15s, background 0.15s;
}
.topbar-link:hover {
  background: var(--c-surface);
  color: var(--c-text);
  text-decoration: none;
}

/* ---------- Layout grid ---------- */
.layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr) var(--toc-w);
  max-width: 1400px;
  margin: 0 auto;
  gap: 2rem;
  padding: 1.5rem 1.25rem 4rem;
  align-items: start;
}

/* ---------- Sidebar ---------- */
.sidebar {
  position: sticky;
  top: calc(var(--topbar-h) + 1rem);
  align-self: start;
  max-height: calc(100vh - var(--topbar-h) - 2rem);
  overflow-y: auto;
  padding-right: 0.5rem;
}

.sidebar nav { display: block; }
.nav-section { margin-bottom: 1.5rem; }
.nav-title {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--c-muted);
  padding: 0.25rem 0.7rem;
  margin-bottom: 0.3rem;
}
.sidebar nav a {
  position: relative;
  display: block;
  padding: 0.4rem 0.7rem;
  border-radius: var(--radius-sm);
  color: var(--c-text-soft);
  font-size: 0.895rem;
  font-weight: 450;
  margin-bottom: 1px;
  transition: background 0.13s, color 0.13s;
}
.sidebar nav a:hover {
  background: var(--c-surface);
  color: var(--c-text);
  text-decoration: none;
}
.sidebar nav a.is-active {
  background: var(--c-primary-soft);
  color: var(--c-primary-dark);
  font-weight: 600;
}
.sidebar nav a.is-active::before {
  content: '';
  position: absolute;
  left: -0.5rem;
  top: 0.45rem;
  bottom: 0.45rem;
  width: 3px;
  border-radius: 3px;
  background: var(--grad);
}
[data-theme="dark"] .sidebar nav a.is-active { color: var(--c-primary); }

/* ---------- Content — floating white sheet on the dotted canvas ---------- */
.content {
  position: relative;
  min-width: 0;
  max-width: var(--content-max);
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 2.4rem 2.75rem 3rem;
  box-shadow: 0 1px 3px rgba(16, 24, 40, 0.04),
              0 14px 44px rgba(16, 24, 40, 0.07);
}
[data-theme="dark"] .content {
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4),
              0 18px 50px rgba(0, 0, 0, 0.45);
}
/* faint brand glow at the top of the sheet (covered by the dark hero on the homepage) */
.content::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 240px;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  background:
    radial-gradient(55% 130% at 92% -10%, color-mix(in srgb, var(--c-primary) 9%, transparent), transparent 70%),
    radial-gradient(45% 120% at 4% -15%, color-mix(in srgb, #18b39a 6%, transparent), transparent 70%);
  pointer-events: none;
  z-index: 0;
}
.content > * { position: relative; z-index: 1; }

.content article > :first-child:not(.hero) { margin-top: 0; }

/* Chapter header — aurora glow panel (echoes the homepage hero, reading-friendly) */
.chapter-header {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  margin: 0 0 2rem;
  padding: 1.7rem 1.85rem 1.55rem;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(60% 130% at 100% -20%, color-mix(in srgb, var(--c-primary) 10%, transparent), transparent 62%),
    radial-gradient(48% 120% at -5% -15%, color-mix(in srgb, #14b8a6 8%, transparent), transparent 60%),
    var(--c-surface);
}
/* drifting aurora */
.chapter-header::before {
  content: '';
  position: absolute;
  inset: -45%;
  z-index: -2;
  background:
    radial-gradient(34% 46% at 80% 16%, color-mix(in srgb, var(--c-primary) 30%, transparent), transparent 60%),
    radial-gradient(40% 50% at 10% 0%, color-mix(in srgb, #18b39a 24%, transparent), transparent 62%);
  filter: blur(42px) saturate(1.1);
  opacity: 0.5;
  animation: heroDrift 22s ease-in-out infinite alternate;
}
[data-theme="dark"] .chapter-header::before { opacity: 0.7; }
/* dot grid fading from the top-right */
.chapter-header::after {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image: radial-gradient(color-mix(in srgb, var(--c-primary) 13%, transparent) 1px, transparent 1.3px);
  background-size: 22px 22px;
  -webkit-mask-image: radial-gradient(95% 80% at 88% 0%, #000, transparent 72%);
  mask-image: radial-gradient(95% 80% at 88% 0%, #000, transparent 72%);
  opacity: 0.65;
  pointer-events: none;
}
.chapter-header > * { position: relative; z-index: 1; }

.chapter-meta {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  color: var(--c-primary-dark);
  background: color-mix(in srgb, var(--c-primary) 10%, #fff);
  border: 1px solid color-mix(in srgb, var(--c-primary) 24%, transparent);
  padding: 0.26rem 0.72rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.chapter-meta::before {
  content: '';
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--c-primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--c-primary) 22%, transparent);
}
[data-theme="dark"] .chapter-meta {
  color: var(--c-primary);
  background: color-mix(in srgb, var(--c-primary) 14%, transparent);
}
.chapter-header h1 {
  margin-top: 0.7rem;
  font-size: 2.15rem;
  letter-spacing: -0.03em;
}
.chapter-header .lead { margin-bottom: 0; }

/* ---------- TOC (right) ---------- */
.toc {
  position: sticky;
  top: calc(var(--topbar-h) + 1rem);
  align-self: start;
  max-height: calc(100vh - var(--topbar-h) - 2rem);
  overflow-y: auto;
  font-size: 0.88rem;
}
.toc-title {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--c-muted);
  margin-bottom: 0.5rem;
  padding: 0 0.5rem;
}
.toc a {
  display: block;
  padding: 0.3rem 0.5rem;
  color: var(--c-muted);
  border-left: 2px solid transparent;
  line-height: 1.4;
}
.toc a:hover { color: var(--c-primary); text-decoration: none; }
.toc a.is-active {
  color: var(--c-primary);
  border-left-color: var(--c-primary);
  font-weight: 600;
}
.toc a.toc-l2 { padding-left: 1rem; }
.toc a.toc-l3 { padding-left: 1.75rem; font-size: 0.83rem; }

/* ---------- Page navigation (prev/next) ---------- */
.page-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--c-border);
}
.page-nav a {
  display: block;
  padding: 0.95rem 1.15rem;
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  background: var(--c-bg);
  color: var(--c-text);
  transition: border-color 0.15s, background 0.15s;
}
.page-nav a:hover {
  border-color: var(--c-border-strong);
  background: var(--c-surface);
  text-decoration: none;
}
.page-nav .label {
  display: block;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--c-muted);
  margin-bottom: 0.25rem;
}
.page-nav .title { font-weight: 600; color: var(--c-text); }
.page-nav .next  { text-align: right; }

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid var(--c-border);
  background: var(--c-surface);
  padding: 2rem 1.25rem;
  color: var(--c-muted);
  font-size: 0.9rem;
}
.footer .footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.footer a { color: var(--c-text-soft); }

/* ---------- Responsive ---------- */
@media (max-width: 1180px) {
  .layout {
    grid-template-columns: var(--sidebar-w) minmax(0, 1fr);
  }
  .toc { display: none; }
}

@media (max-width: 860px) {
  .menu-toggle { display: inline-flex; align-items: center; justify-content: center; }
  .layout {
    grid-template-columns: minmax(0, 1fr);
    padding: 1rem 0.85rem 3rem;
  }
  .content { padding: 1.5rem 1.25rem 2rem; }
  .sidebar {
    position: fixed;
    top: var(--topbar-h);
    left: 0;
    width: min(86vw, 320px);
    height: calc(100vh - var(--topbar-h));
    max-height: none;
    background: var(--c-bg);
    border-right: 1px solid var(--c-border);
    box-shadow: var(--shadow-lg);
    padding: 1.25rem 1rem;
    transform: translateX(-100%);
    transition: transform 0.25s ease;
    z-index: 40;
  }
  .sidebar.is-open { transform: translateX(0); }
  .sidebar-backdrop {
    display: none;
    position: fixed;
    inset: var(--topbar-h) 0 0 0;
    background: rgba(15, 23, 42, 0.4);
    z-index: 39;
  }
  .sidebar-backdrop.is-visible { display: block; }
  /* Hide text labels but keep search button */
  .topbar-actions .topbar-link { display: none; }
}

@media (max-width: 540px) {
  h1 { font-size: 1.7rem; }
  h2 { font-size: 1.3rem; }
  body { font-size: 15.5px; }

  /* Topbar fits on one line: hide sub-label, keep brand on a single row,
     tighten gaps so the 🌙/✨ toggles stay on-screen */
  .topbar-inner { gap: 0.5rem; padding: 0 0.85rem; }
  .brand { padding-left: 0.7rem; }
  .brand-mark { white-space: nowrap; font-size: 1rem; }
  .brand-sub { display: none; }
  .topbar-actions { gap: 0.25rem; margin-left: auto; }
}

/* ---------- Print stylesheet ---------- */
@media print {
  /* Hide interactive chrome */
  .topbar, .sidebar, .toc, .page-nav, .menu-toggle,
  .topbar-actions, .footer, .search-overlay, .copy-btn,
  .sidebar-backdrop { display: none !important; }

  body {
    font-size: 10.5pt;
    color: #000;
    background: #fff;
  }

  .layout {
    display: block !important;
    grid-template-columns: none !important;
    max-width: 100% !important;
    margin: 0 !important;
    padding: 0 !important;
  }
  .content {
    max-width: 100% !important;
  }

  /* Code blocks: light bg for printer ink saving */
  pre {
    background: #f5f5f5 !important;
    color: #1f2937 !important;
    border: 1px solid #ccc;
    page-break-inside: avoid;
  }
  pre .token.comment   { color: #6b7280 !important; }
  pre .token.keyword   { color: #9333ea !important; }
  pre .token.string    { color: #b45309 !important; }
  pre .token.function  { color: #1d4ed8 !important; }
  pre .token.number    { color: #047857 !important; }
  pre .token.operator,
  pre .token.punctuation { color: #1f2937 !important; }

  a {
    color: #0E7C66 !important;
    text-decoration: underline;
  }
  /* Show URL after links */
  a[href^="http"]::after {
    content: " (" attr(href) ")";
    font-size: 0.8em;
    color: #555;
  }

  /* Callouts: simple border, no bg */
  .callout {
    background: transparent !important;
    border-left-width: 3px !important;
    page-break-inside: avoid;
  }
  figure, table, .table-wrap, .card-grid, .spec-grid {
    page-break-inside: avoid;
  }
  h1, h2, h3 { page-break-after: avoid; }

  /* Print only: ensure each h1 starts a new page (chapter break) */
  article > section { page-break-before: auto; }
  .chapter-header { page-break-before: auto; }
}