/* ===== CSS Variables / Theme ===== */
:root {
  --sidebar-width: 280px;
  --topbar-height: 56px;
  --color-bg: #ffffff;
  --color-bg-alt: #f7fafc;
  --color-sidebar-bg: #1a202c;
  --color-sidebar-text: #cbd5e0;
  --color-sidebar-active: #63b3ed;
  --color-sidebar-hover-bg: rgba(99,179,237,0.1);
  --color-topbar-bg: #1a365d;
  --color-topbar-text: #ffffff;
  --color-text: #2d3748;
  --color-text-muted: #718096;
  --color-heading: #1a365d;
  --color-link: #3182ce;
  --color-link-hover: #2c5282;
  --color-border: #e2e8f0;
  --color-code-bg: #edf2f7;
  --color-code-text: #c53030;
  --color-pre-bg: #1a202c;
  --color-pre-text: #e2e8f0;
  --color-blockquote-border: #3182ce;
  --color-blockquote-bg: #ebf8ff;
  --color-table-header-bg: #1a365d;
  --color-table-header-text: #ffffff;
  --color-table-stripe: #f7fafc;
  --color-badge: #3182ce;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
  --radius: 6px;
  --transition: 0.2s ease;
}

[data-theme="dark"] {
  --color-bg: #1a202c;
  --color-bg-alt: #2d3748;
  --color-sidebar-bg: #0d1117;
  --color-sidebar-text: #8b949e;
  --color-sidebar-active: #63b3ed;
  --color-sidebar-hover-bg: rgba(99,179,237,0.08);
  --color-topbar-bg: #0d1117;
  --color-topbar-text: #e2e8f0;
  --color-text: #e2e8f0;
  --color-text-muted: #a0aec0;
  --color-heading: #90cdf4;
  --color-link: #63b3ed;
  --color-link-hover: #90cdf4;
  --color-border: #4a5568;
  --color-code-bg: #2d3748;
  --color-code-text: #fc8181;
  --color-pre-bg: #0d1117;
  --color-pre-text: #e2e8f0;
  --color-blockquote-border: #63b3ed;
  --color-blockquote-bg: rgba(99,179,237,0.08);
  --color-table-header-bg: #2d3748;
  --color-table-header-text: #e2e8f0;
  --color-table-stripe: #2d3748;
  --color-badge: #63b3ed;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--topbar-height) + 24px);
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* ===== Top Bar ===== */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--topbar-height);
  background: var(--color-topbar-bg);
  color: var(--color-topbar-text);
  display: flex;
  align-items: center;
  padding: 0 24px;
  z-index: 1000;
  box-shadow: var(--shadow-md);
  gap: 16px;
}

.topbar-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  white-space: nowrap;
  flex-shrink: 0;
  text-decoration: none;
  color: inherit;
}

.topbar-brand svg { width: 28px; height: 28px; }

.topbar-brand .brand-sub {
  font-weight: 400;
  font-size: 0.8rem;
  opacity: 0.7;
  margin-left: 4px;
}

.topbar-search {
  flex: 1;
  max-width: 420px;
  position: relative;
  margin-left: auto;
}

.topbar-search input {
  width: 100%;
  padding: 7px 14px 7px 36px;
  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 8px;
  background: rgba(255,255,255,0.08);
  color: #fff;
  font-size: 0.875rem;
  outline: none;
  transition: var(--transition);
}

.topbar-search input::placeholder { color: rgba(255,255,255,0.45); }
.topbar-search input:focus {
  background: rgba(255,255,255,0.14);
  border-color: rgba(99,179,237,0.5);
  box-shadow: 0 0 0 3px rgba(99,179,237,0.15);
}

.topbar-search .search-icon {
  position: absolute;
  left: 11px;
  top: 50%;
  transform: translateY(-50%);
  opacity: 0.45;
  pointer-events: none;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.theme-toggle {
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.15);
  color: #fff;
  width: 34px; height: 34px;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  transition: var(--transition);
}

.theme-toggle:hover { background: rgba(255,255,255,0.18); }

.hamburger {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 4px;
  line-height: 1;
}

/* ===== Sidebar ===== */
.sidebar {
  position: fixed;
  top: var(--topbar-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--topbar-height));
  background: var(--color-sidebar-bg);
  overflow-y: auto;
  z-index: 900;
  border-right: 1px solid rgba(255,255,255,0.06);
  padding: 16px 0;
  transition: transform 0.3s ease;
  scrollbar-width: thin;
  scrollbar-color: rgba(255,255,255,0.15) transparent;
}

.sidebar::-webkit-scrollbar { width: 5px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.15); border-radius: 3px; }

.sidebar-label {
  padding: 8px 20px 6px;
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: rgba(255,255,255,0.3);
  font-weight: 600;
}

.nav-item {
  display: block;
  padding: 6px 20px;
  color: var(--color-sidebar-text);
  text-decoration: none;
  font-size: 0.84rem;
  border-left: 3px solid transparent;
  transition: var(--transition);
  line-height: 1.4;
}

.nav-item:hover {
  color: #fff;
  background: var(--color-sidebar-hover-bg);
}

.nav-item.active {
  color: var(--color-sidebar-active);
  border-left-color: var(--color-sidebar-active);
  background: var(--color-sidebar-hover-bg);
  font-weight: 600;
}

.nav-item.level-1 {
  font-size: 0.88rem;
  font-weight: 700;
  padding: 10px 20px;
  color: #e2e8f0;
  margin-top: 4px;
}

.nav-item.level-2 {
  font-weight: 600;
  padding-left: 20px;
  margin-top: 10px;
  font-size: 0.8rem;
  color: #a0aec0;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.nav-item.level-3 {
  padding-left: 32px;
  font-size: 0.8rem;
}

/* ===== Search Results ===== */
.search-results {
  display: none;
  position: fixed;
  top: var(--topbar-height);
  left: var(--sidebar-width);
  right: 0;
  background: var(--color-bg);
  border-bottom: 2px solid var(--color-border);
  max-height: 400px;
  overflow-y: auto;
  z-index: 800;
  box-shadow: var(--shadow-lg);
  padding: 12px 0;
}

.search-results.visible { display: block; }

.search-result-item {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 10px 24px;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  color: var(--color-text);
}

.search-result-item:hover { background: var(--color-bg-alt); }

.search-result-item .result-badge {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  background: var(--color-badge);
  color: #fff;
  padding: 2px 7px;
  border-radius: 4px;
  white-space: nowrap;
  flex-shrink: 0;
}

.search-result-item .result-text { font-size: 0.9rem; }

.search-result-item .result-text mark {
  background: #fefcbf;
  color: #744210;
  padding: 1px 2px;
  border-radius: 2px;
}

[data-theme="dark"] .search-result-item .result-text mark {
  background: rgba(250,240,137,0.2);
  color: #fefcbf;
}

.search-no-results {
  padding: 20px 24px;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ===== Main Content ===== */
.main {
  margin-left: var(--sidebar-width);
  margin-top: var(--topbar-height);
  min-height: calc(100vh - var(--topbar-height));
  padding: 32px 56px 60px;
  max-width: 900px;
}

/* Breadcrumb */
.breadcrumb {
  margin-bottom: 24px;
  font-size: 0.82rem;
}

.breadcrumb ol {
  display: flex;
  align-items: center;
  list-style: none;
  gap: 6px;
  padding: 0;
  margin: 0;
}

.breadcrumb li + li::before {
  content: "/";
  color: var(--color-text-muted);
  margin-right: 6px;
}

.breadcrumb a {
  color: var(--color-link);
  text-decoration: none;
}

.breadcrumb a:hover { text-decoration: underline; }

.breadcrumb .current {
  color: var(--color-text-muted);
}

/* Headings */
.main h1 {
  font-size: 2rem;
  color: var(--color-heading);
  margin: 0 0 16px;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
  padding-bottom: 12px;
  border-bottom: 3px solid var(--color-border);
}

.main h2 {
  font-size: 1.5rem;
  color: var(--color-heading);
  margin: 0 0 16px;
  font-weight: 700;
  letter-spacing: -0.01em;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-border);
  line-height: 1.3;
}

.main h3 {
  font-size: 1.15rem;
  color: var(--color-heading);
  margin: 32px 0 12px;
  font-weight: 600;
  line-height: 1.35;
}

.main h4, .main h5, .main h6 {
  font-size: 1rem;
  color: var(--color-heading);
  margin: 24px 0 8px;
  font-weight: 600;
}

.anchor {
  color: var(--color-link);
  text-decoration: none;
  opacity: 0;
  margin-right: 8px;
  font-weight: 400;
  transition: opacity var(--transition);
}
h1:hover .anchor, h2:hover .anchor, h3:hover .anchor,
h4:hover .anchor, h5:hover .anchor, h6:hover .anchor { opacity: 0.5; }
.anchor:hover { opacity: 1 !important; }

.main p { margin: 0 0 16px; line-height: 1.75; }

.main a {
  color: var(--color-link);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: var(--transition);
}
.main a:hover {
  color: var(--color-link-hover);
  border-bottom-color: var(--color-link-hover);
}

.main ul, .main ol { margin: 0 0 16px; padding-left: 24px; }
.main li { margin-bottom: 6px; line-height: 1.65; }
.main li::marker { color: var(--color-badge); }

.main code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--color-code-bg);
  color: var(--color-code-text);
  padding: 2px 6px;
  border-radius: 4px;
}

.main pre {
  background: var(--color-pre-bg);
  color: var(--color-pre-text);
  padding: 20px 24px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 0 0 20px;
  font-size: 0.85rem;
  line-height: 1.55;
  box-shadow: var(--shadow-sm);
  border: 1px solid rgba(255,255,255,0.06);
}

.main pre code {
  background: none;
  color: inherit;
  padding: 0;
  font-size: inherit;
}

.main blockquote {
  border-left: 4px solid var(--color-blockquote-border);
  background: var(--color-blockquote-bg);
  padding: 16px 20px;
  margin: 0 0 20px;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-style: italic;
}

.main blockquote p { margin: 0; color: var(--color-text); }

.table-wrap {
  overflow-x: auto;
  margin: 0 0 20px;
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
}

.main table { width: 100%; border-collapse: collapse; font-size: 0.875rem; }

.main thead th {
  background: var(--color-table-header-bg);
  color: var(--color-table-header-text);
  padding: 10px 16px;
  text-align: left;
  font-weight: 600;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.main tbody td {
  padding: 10px 16px;
  border-top: 1px solid var(--color-border);
}

.main tbody tr:nth-child(even) { background: var(--color-table-stripe); }
.main tbody tr:hover { background: var(--color-blockquote-bg); }

.main hr {
  border: none;
  border-top: 2px solid var(--color-border);
  margin: 40px 0;
}

.main strong {
  font-weight: 600;
  color: var(--color-heading);
}

/* ===== Page Navigation (Prev/Next) ===== */
.page-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 24px;
  border-top: 2px solid var(--color-border);
}

.page-nav-link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 14px 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--color-text);
  transition: var(--transition);
  max-width: 48%;
  min-width: 0;
}

.page-nav-link:hover {
  border-color: var(--color-link);
  background: var(--color-bg-alt);
  box-shadow: var(--shadow-sm);
}

.page-nav-link.next { text-align: right; margin-left: auto; }

.page-nav-label {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  font-weight: 600;
}

.page-nav-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-link);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ===== Home page cards ===== */
.section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
  margin: 28px 0;
}

.section-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 18px 20px;
  text-decoration: none;
  color: var(--color-text);
  transition: var(--transition);
  display: block;
}

.section-card:hover {
  border-color: var(--color-link);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.section-card-title {
  font-weight: 600;
  font-size: 0.92rem;
  color: var(--color-heading);
  margin-bottom: 6px;
}

.section-card-desc {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  line-height: 1.45;
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 28px; right: 28px;
  width: 42px; height: 42px;
  background: var(--color-topbar-bg);
  color: #fff;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.3s, transform 0.3s;
  z-index: 500;
  font-size: 1.1rem;
}

.back-to-top.visible { opacity: 1; transform: translateY(0); }
.back-to-top:hover { background: var(--color-link); box-shadow: var(--shadow-lg); }

/* ===== Footer ===== */
.footer {
  margin-left: var(--sidebar-width);
  padding: 24px 56px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 0.8rem;
  text-align: center;
}

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 899;
}

/* ===== Mobile ===== */
@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .sidebar-overlay.open { display: block; }
  .hamburger { display: block; }
  .main { margin-left: 0; padding: 24px 20px 60px; }
  .footer { margin-left: 0; padding: 20px; }
  .search-results { left: 0; }
  .main h1 { font-size: 1.55rem; }
  .main h2 { font-size: 1.2rem; }
  .page-nav { flex-direction: column; }
  .page-nav-link { max-width: 100%; }
  .page-nav-link.next { text-align: left; }
  .section-grid { grid-template-columns: 1fr; }
}

/* ===== Screenshot Images ===== */
.doc-figure {
  margin: 1.25rem 0 1.75rem;
  padding: 0;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: box-shadow var(--transition), border-color var(--transition);
}
.doc-figure:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-link);
}
.doc-figure-img-wrap {
  position: relative;
  cursor: zoom-in;
  overflow: hidden;
}
.doc-figure-img-wrap::after {
  content: "\1F50D Click to enlarge";
  position: absolute;
  bottom: 0;
  right: 0;
  padding: 4px 10px;
  font-size: 0.7rem;
  font-family: var(--font-sans);
  color: #fff;
  background: rgba(0,0,0,0.55);
  border-radius: var(--radius) 0 0 0;
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
}
.doc-figure-img-wrap:hover::after {
  opacity: 1;
}
.doc-figure img {
  display: block;
  width: 100%;
  height: auto;
}
.doc-figure figcaption {
  padding: 0.5rem 0.75rem;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: 6px;
}
.doc-figure figcaption svg {
  flex-shrink: 0;
}

/* Screenshot modal */
.screenshot-modal-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 10000;
  background: rgba(0,0,0,0.82);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  cursor: zoom-out;
  animation: modalFadeIn 0.2s ease;
}
.screenshot-modal-backdrop.active {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
@keyframes modalFadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}
.screenshot-modal-content {
  position: relative;
  max-width: 94vw;
  max-height: 88vh;
  animation: modalZoomIn 0.25s ease;
}
@keyframes modalZoomIn {
  from { transform: scale(0.92); opacity: 0; }
  to   { transform: scale(1); opacity: 1; }
}
.screenshot-modal-content img {
  display: block;
  max-width: 94vw;
  max-height: 86vh;
  border-radius: 8px;
  box-shadow: 0 12px 48px rgba(0,0,0,0.5);
  object-fit: contain;
}
.screenshot-modal-caption {
  margin-top: 12px;
  color: rgba(255,255,255,0.8);
  font-size: 0.85rem;
  font-family: var(--font-sans);
  text-align: center;
}
.screenshot-modal-close {
  position: absolute;
  top: -14px;
  right: -14px;
  width: 32px;
  height: 32px;
  border: none;
  border-radius: 50%;
  background: rgba(255,255,255,0.15);
  color: #fff;
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition);
  z-index: 1;
}
.screenshot-modal-close:hover {
  background: rgba(255,255,255,0.3);
}

/* ===== Print ===== */
@media print {
  .topbar, .sidebar, .sidebar-overlay, .back-to-top, .hamburger,
  .topbar-search, .theme-toggle, .anchor, .page-nav, .breadcrumb { display: none !important; }
  .main { margin: 0; padding: 20px; max-width: 100%; }
  .footer { margin-left: 0; }
  body { color: #000; background: #fff; }
  .main h1, .main h2, .main h3 { color: #000; break-after: avoid; }
  .main pre { border: 1px solid #ccc; background: #f5f5f5; color: #000; }
  .table-wrap { box-shadow: none; }
}