/* ---------- Skip link ---------- */
.skip-link {
  position: absolute;
  top: 0;
  left: 0;
  padding: 0.5rem 0.75rem;
  background: var(--accent);
  color: var(--bg-color);
  text-decoration: none;
  border-radius: 0 0 6px 0;
  font-weight: 600;
  font-size: 0.9rem;
  transform: translateY(-100%);
  transition: transform 0.15s ease;
  z-index: 200;
}
.skip-link:focus { transform: translateY(0); outline: none; }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg-color) 85%, transparent);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--border-color);
}
@supports not (background: color-mix(in srgb, red, blue)) {
  .site-header { background: var(--bg-color); }
}

.header-inner {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 2rem;
  height: var(--header-height);
  display: flex;
  align-items: center;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
  font-size: 1.1rem;
  margin-right: auto;
}

.brand-logo { height: 56px; width: auto; display: block; }
.brand-name { letter-spacing: -0.02em; }

@media (max-width: 480px) {
  .brand-name { display: none; }
}

/* ---------- Version selector ---------- */
.version-selector {
  position: relative;
  margin-left: 0.25rem;
}
.version-selector[hidden] { display: none; }

.version-selector-trigger {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  border-radius: 6px;
  padding: 0.25rem 0.55rem;
  font: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}
.version-selector-trigger:hover { border-color: var(--accent); }
.version-selector-trigger[aria-expanded="true"] { border-color: var(--accent); }

.version-selector-menu {
  position: absolute;
  top: calc(100% + 0.4rem);
  left: 0;
  min-width: 100%;
  list-style: none;
  margin: 0;
  padding: 0.3rem;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
  z-index: 60;
  max-height: 60vh;
  overflow-y: auto;
}
.version-selector-menu[hidden] { display: none; }

.version-selector-item {
  display: block;
  padding: 0.35rem 0.6rem;
  border-radius: 4px;
  text-decoration: none;
  color: var(--text-primary);
  font-size: 0.85rem;
  white-space: nowrap;
}
.version-selector-item:hover { background: var(--bg-color); }
.version-selector-item.is-current {
  font-weight: 600;
  color: var(--accent);
}
.version-selector-alias {
  color: var(--text-secondary);
  font-weight: 400;
  margin-left: 0.4rem;
  font-size: 0.75rem;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  border-radius: 8px;
  padding: 0.4rem;
  cursor: pointer;
  align-items: center;
  justify-content: center;
}
.nav-toggle:hover { border-color: var(--accent); }

.search-trigger {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  border-radius: 8px;
  padding: 0.4rem 0.7rem;
  font: inherit;
  font-size: 0.9rem;
  cursor: pointer;
  transition: var(--transition);
}
.search-trigger:hover { border-color: var(--accent); color: var(--accent); }
.search-trigger-key {
  font-family: 'Ubuntu Mono', ui-monospace, SFMono-Regular, monospace;
  font-size: 0.75rem;
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  padding: 0.05rem 0.35rem;
  color: var(--text-secondary);
}

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

.layout > .content { min-width: 0; padding-top: 1.5rem; }
.layout:has(> .sidebar:only-of-type):not(:has(> .toc)) { grid-template-columns: var(--sidebar-width) 1fr; }
.layout:not(:has(> .sidebar)):has(> .toc) { grid-template-columns: 1fr var(--toc-width); }
.layout:not(:has(> .sidebar)):not(:has(> .toc)) { grid-template-columns: 1fr; }

/* ---------- Sidebar nav ---------- */
.sidebar {
  position: sticky;
  top: var(--header-height);
  max-height: calc(100vh - var(--header-height));
  overflow-y: auto;
  padding: 1.5rem 0;
}

.sidebar-inner { padding-right: 1rem; }

.nav-list { list-style: none; padding: 0; margin: 0; }
.nav-list .nav-list { padding-left: 0.75rem; margin-top: 0.25rem; border-left: 1px solid var(--border-color); }

.nav-item { margin: 0.1rem 0; }

.nav-section-title {
  display: block;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin: 1rem 0 0.4rem;
}

.nav-link {
  display: block;
  padding: 0.35rem 0.75rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: 6px;
  font-size: 0.95rem;
  position: relative;
  transition: color 0.15s ease, background-color 0.15s ease;
}
.nav-link:hover { color: var(--accent); background: var(--card-bg); }
.nav-link.is-active {
  color: var(--accent);
  background: var(--card-bg);
  font-weight: 600;
}
.nav-link.is-active::before {
  content: '';
  position: absolute;
  left: -1px;
  top: 6px;
  bottom: 6px;
  width: 3px;
  background: var(--accent);
  border-radius: 2px;
}

/* ---------- TOC ---------- */
.toc {
  position: sticky;
  top: var(--header-height);
  max-height: calc(100vh - var(--header-height));
  overflow-y: auto;
  padding: 1.5rem 0;
  font-size: 0.9rem;
}
.toc-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}
.toc-list { list-style: none; padding: 0; margin: 0; }
.toc-list .toc-list { padding-left: 0.75rem; }
.toc-link {
  display: block;
  padding: 0.2rem 0;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.15s ease;
}
.toc-link:hover { color: var(--accent); }

/* ---------- Pagination ---------- */
.pagination {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 3rem auto 4rem;
  max-width: var(--content-width);
}
.pagination > a {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1rem 1.25rem;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  transition: var(--transition);
}
.pagination > a:hover { border-color: var(--accent); transform: translateY(-2px); }
.pagination-prev { text-align: left; }
.pagination-next { text-align: right; grid-column: 2; }
.pagination-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}
.pagination-title { font-weight: 600; color: var(--accent); }

/* ---------- Search modal ---------- */
.search-modal[hidden] { display: none; }
.search-modal {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding-top: 10vh;
}
.search-modal-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(4px);
}
.search-modal-panel {
  position: relative;
  background: var(--card-bg);
  border-radius: 12px;
  border: 1px solid var(--border-color);
  width: 90%;
  max-width: 600px;
  max-height: 70vh;
  display: flex;
  flex-direction: column;
  box-shadow: 0 20px 60px rgba(0,0,0,.2);
}
.search-modal-input-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-secondary);
}
.search-modal-input {
  flex: 1;
  border: 0;
  outline: 0;
  background: transparent;
  font: inherit;
  font-size: 1rem;
  color: var(--text-primary);
}
.search-modal-close {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 0.2rem 0.5rem;
  font: inherit;
  font-size: 0.75rem;
  color: var(--text-secondary);
  cursor: pointer;
}
.search-modal-results {
  overflow-y: auto;
  padding: 0.5rem;
}
.search-result {
  display: block;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  text-decoration: none;
  color: inherit;
  border: 1px solid transparent;
}
.search-result:hover, .search-result.is-active {
  background: var(--bg-color);
  border-color: var(--border-color);
}
.search-result-title { font-weight: 600; color: var(--text-primary); }
.search-result-text  { font-size: 0.85rem; color: var(--text-secondary); margin-top: 0.25rem; }
.search-empty { padding: 1.5rem; text-align: center; color: var(--text-secondary); }

/* ---------- Mobile ---------- */
@media (max-width: 960px) {
  .layout { grid-template-columns: 1fr !important; gap: 0; padding: 0 1.25rem; }
  .toc { display: none; }
  .sidebar {
    position: fixed;
    top: var(--header-height);
    left: 0;
    bottom: 0;
    width: 80%;
    max-width: 320px;
    background: var(--bg-color);
    border-right: 1px solid var(--border-color);
    transform: translateX(-100%);
    transition: transform 0.25s ease;
    z-index: 40;
    padding: 1rem 1.25rem;
  }
  .sidebar.is-open { transform: translateX(0); }
  .nav-toggle { display: inline-flex; }
  body.nav-open { overflow: hidden; }
}

@media (max-width: 640px) {
  .header-inner { padding: 0 1rem; gap: 0.5rem; }
  .search-trigger-label { display: none; }
  .search-trigger-key { display: none; }
  .pagination { grid-template-columns: 1fr; }
  .pagination-next { grid-column: 1; }
}