/* ===== HEADER ===== */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 40;
  height: calc(var(--header-h) + var(--safe-top));
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  pointer-events: none;
}

.site-header::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: var(--accent);
}

.site-header > * { pointer-events: auto; }

.header-inner {
  min-height: var(--header-h);
  height: 100%;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding-top: var(--safe-top);
}

.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 36px;
  height: 36px;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: 0;
  background: var(--bg-card);
  cursor: pointer;
  flex-shrink: 0;
  transition: border-color 0.2s, background 0.2s;
}

.hamburger:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.hamburger-bar {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--ink);
  border-radius: 0;
  transition: transform 0.2s, opacity 0.2s;
}

.header-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* --- Brand --- */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  min-width: 0;
  cursor: pointer;
}

.brand:hover .brand-mark {
  background: var(--accent);
}

.brand-mark {
  width: 36px;
  height: 36px;
  border: 1px solid var(--border-strong);
  background: var(--ink);
  color: var(--bg);
  display: grid;
  place-items: center;
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  transition: background 0.2s;
}

.brand-lockup {
  display: grid;
  gap: 0.06rem;
  min-width: 0;
}

.brand-text {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.58rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

/* --- Theme Toggle --- */
.theme-toggle {
  display: flex;
  border: 1px solid var(--border);
}

.theme-toggle-btn {
  border: none;
  border-right: 1px solid var(--border);
  padding: 0.3rem 0.55rem;
  background: transparent;
  color: var(--ink-faint);
  font-family: var(--font-mono);
  font-size: 0.6rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.theme-toggle-btn:last-child {
  border-right: none;
}

.theme-toggle-btn:hover {
  background: var(--accent-soft);
  color: var(--accent);
}

.theme-toggle-btn.is-active {
  background: var(--ink);
  color: var(--bg);
}

/* --- Sidebar Close Button --- */
.toc-close-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--ink);
  cursor: pointer;
  flex-shrink: 0;
  transition: border-color 0.15s;
}

.toc-close-btn:hover {
  border-color: var(--accent);
}

/* ===== SIDEBAR OVERLAY ===== */
.sidebar-overlay {
  position: fixed;
  inset: 0;
  z-index: 50;
  background: rgba(0, 0, 0, 0.35);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}

.sidebar-overlay.is-visible {
  opacity: 1;
  pointer-events: auto;
}

/* ===== SIDEBAR ===== */
.toc-sidebar {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 60;
  width: min(36vw, 420px);
  height: 100dvh;
  padding-top: var(--safe-top);
  padding-bottom: var(--safe-bottom);
  background: var(--bg);
  border-right: 1px solid var(--border-strong);
  display: grid;
  grid-template-rows: auto 1fr auto;
  transform: translateX(-102%);
  transition: transform 0.3s var(--ease-spring);
}

.toc-sidebar::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: var(--accent);
}

.toc-sidebar.is-open {
  transform: translateX(0);
}

.toc-head {
  padding: 0.85rem 1rem 0.75rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.toc-title {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink);
}

.toc-body {
  overflow-y: auto;
  overflow-x: hidden;
  padding: 0.8rem 0.85rem 1rem;
  scrollbar-width: thin;
  scrollbar-color: var(--border-strong) transparent;
}

.toc-section {
  margin-bottom: 1rem;
}

.toc-section:last-child { margin-bottom: 0; }

.toc-heading {
  margin-bottom: 0.25rem;
}

.toc-num {
  color: var(--accent);
  font-weight: 500;
}

.toc-heading-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  border: 0;
  border-bottom: 1px solid var(--border);
  background: transparent;
  color: inherit;
  padding: 0 0 0.3rem;
  cursor: pointer;
  text-align: left;
}

.toc-heading-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.toc-heading-label {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: 0.02em;
  color: var(--ink);
}

.toc-chevron {
  width: 8px;
  height: 8px;
  border-right: 1.5px solid var(--ink-faint);
  border-bottom: 1.5px solid var(--ink-faint);
  transform: rotate(45deg);
  transition: transform 0.18s ease;
  flex-shrink: 0;
}

.toc-heading-btn[aria-expanded="false"] .toc-chevron {
  transform: rotate(-45deg) translateY(1px);
}

.toc-section-body[hidden] {
  display: none;
}

.toc-items {
  list-style: none;
  display: grid;
  gap: 1px;
  padding-left: 0;
}

.toc-item-group {
  list-style: none;
}

.toc-subtree {
  border: 1px solid transparent;
  transition: border-color 0.15s, background 0.15s;
}

.toc-subtree[open] {
  border-color: var(--border);
  background: var(--accent-soft);
}

.toc-subtree-summary {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  justify-content: space-between;
  padding: 0.35rem 0.5rem;
  cursor: pointer;
  user-select: none;
  list-style: none;
}

.toc-subtree-summary::-webkit-details-marker {
  display: none;
}

.toc-subtree-summary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.toc-subtree-summary .toc-item-label {
  flex: 1;
  font-weight: 600;
}

.toc-sub-chevron {
  width: 7px;
  height: 7px;
  border-right: 1.5px solid var(--ink-faint);
  border-bottom: 1.5px solid var(--ink-faint);
  transform: rotate(45deg);
  transition: transform 0.17s ease;
  flex-shrink: 0;
  margin-right: 1px;
}

.toc-subtree[open] .toc-sub-chevron {
  transform: rotate(225deg) translateY(-1px);
}

.toc-items--nested {
  padding: 0 0.3rem 0.25rem 0.5rem;
}

.toc-items--nested .toc-item {
  font-size: 0.78rem;
  padding: 0.3rem 0.45rem;
}

.toc-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.5rem;
  border: 1px solid transparent;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--ink);
  transition: background 0.15s, border-color 0.15s;
}

.toc-item:hover {
  background: var(--accent-soft);
  border-color: var(--border);
}

.toc-item[aria-current="page"] {
  background: var(--highlight);
  border-color: var(--border-strong);
  border-left: 2px solid var(--accent);
  font-weight: 600;
}

.toc-item-label { flex: 1; }

.toc-note {
  font-size: 0.58rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-faint);
  border: 1px solid var(--border);
  padding: 0.06rem 0.3rem;
  background: var(--bg-alt);
}

.toc-foot {
  padding: 0.55rem 0.85rem;
  border-top: 1px solid var(--border);
  font-size: 0.65rem;
  color: var(--ink-faint);
}

/* ===== MAIN CONTENT ===== */
.main {
  padding-top: calc(var(--header-h) + var(--safe-top) + 0.8rem);
  padding-bottom: max(0.75rem, var(--safe-bottom));
  min-height: 100dvh;
}

/* ===== HERO ===== */
.hero {
  padding: clamp(1.2rem, 3vw, 2.2rem);
  text-align: left;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.55rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: var(--accent);
}

.hero > * {
  position: relative;
  z-index: 1;
}

.hero .t-display {
  max-width: 17ch;
  margin-top: 0.25rem;
}

.hero-copy {
  max-width: 66ch;
  color: var(--ink-soft);
  font-size: 0.88rem;
  line-height: 1.65;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-start;
  gap: 0.45rem;
  margin-top: 0.45rem;
}

/* ===== SECTION BLOCK ===== */
.section {
  padding: var(--pad-v) 0;
}

.section-head {
  margin-bottom: 1rem;
  padding-bottom: 0.55rem;
  border-bottom: 1px solid var(--border);
}

/* ===== QUICK GRID (home cards) ===== */
.quick-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1px;
  border: 1px solid var(--border);
  background: var(--border);
}

.quick-card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 0.85rem;
  border: none;
  background: var(--bg-card);
  transition: background 0.2s;
  overflow: hidden;
}

.quick-card::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: transparent;
  transition: background 0.2s;
}

.quick-card:hover {
  background: var(--highlight);
}

.quick-card:hover::before {
  background: var(--accent);
}

.quick-card-num {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.08em;
  margin-top: 0.1rem;
}

.quick-card-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  line-height: 1.12;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.quick-card-copy {
  font-size: 0.78rem;
  color: var(--ink-soft);
  line-height: 1.5;
}

/* ===== GOLD STRIP → accent rule ===== */
.gold-strip {
  height: 1px;
  background: var(--border);
  border-radius: 0;
  opacity: 1;
}

/* ===== FOOTER ===== */
.page-footer {
  padding: 1.5rem 0 1rem;
  text-align: left;
  font-size: 0.75rem;
  color: var(--ink-faint);
  border-top: 1px solid var(--border);
  margin-top: 1rem;
}

.page-footer a {
  text-decoration: underline;
  text-decoration-color: var(--border);
  text-underline-offset: 3px;
  transition: color 0.2s;
}

.page-footer a:hover { color: var(--accent); }

/* ===== RESPONSIVE ===== */
@media (max-width: 800px) {
  .toc-sidebar {
    width: min(85vw, 400px);
  }

  .brand-sub { display: none; }

  .hero .t-display {
    font-size: clamp(2.2rem, 10vw, 3.2rem);
  }

  .hero-copy {
    max-width: 100%;
  }
}

@media (max-width: 480px) {
  .toc-sidebar { width: 90vw; }
  .brand-mark {
    width: 32px;
    height: 32px;
    font-size: 0.6rem;
  }
  .page-footer {
    text-align: center;
  }
  .theme-toggle-btn {
    padding: 0.25rem 0.4rem;
    font-size: 0.55rem;
  }
}