/* ==========================================================================
   1. CSS Custom Properties — Light & Dark Themes
   ========================================================================== */

:root {
  --bg: #faf9f7;
  --surface: #f2f0ec;
  --surface-card: #ffffff;
  --text: #1a1a2e;
  --text-secondary: #5a5a72;
  --text-muted: #8e8ea0;
  --accent: #d97706;
  --accent-hover: #b45309;
  --accent-subtle: #fef3c7;
  --border: #e4e2dd;
  --border-light: #eceae5;
  --code-bg: #f2f0ec;
  --font-body: 'DM Sans', system-ui, -apple-system, sans-serif;
  --font-display: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
}

[data-theme="dark"] {
  --bg: #0f0f1a;
  --surface: #161625;
  --surface-card: #1c1c30;
  --text: #e8e8f0;
  --text-secondary: #a0a0b8;
  --text-muted: #6e6e88;
  --accent: #f59e0b;
  --accent-hover: #fbbf24;
  --accent-subtle: rgba(245, 158, 11, 0.1);
  --border: #2a2a42;
  --border-light: #222238;
  --code-bg: #1c1c30;
}

/* ==========================================================================
   2. Reset & Base
   ========================================================================== */

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

html {
  font-size: 16px;
  line-height: 1.6;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ==========================================================================
   3. Skip-to-Content Link
   ========================================================================== */

.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  z-index: 1000;
  padding: 0.75rem 1.5rem;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  border-radius: 4px;
  font-weight: 600;
}

.skip-link:focus {
  top: 12px;
}

/* ==========================================================================
   4. Header
   ========================================================================== */

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}

.logo-link {
  text-decoration: none;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-icon {
  display: block;
}

.site-title {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 700;
}

.hamburger {
  display: none;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 4px;
  width: 40px;
  height: 40px;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text);
}

.hamburger span {
  display: block;
  width: 20px;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
  transition: transform 0.2s, opacity 0.2s;
}

.search-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text-secondary);
}

/* ==========================================================================
   5. Three-Column Layout
   ========================================================================== */

.layout {
  display: grid;
  grid-template-columns: 240px 1fr 200px;
  padding-top: 60px;
  min-height: 100vh;
}

/* ==========================================================================
   6. Sidebar
   ========================================================================== */

.sidebar {
  height: calc(100vh - 60px);
  position: sticky;
  top: 60px;
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border-right: 1px solid var(--border);
}

.sidebar-nav {
  flex: 1;
  overflow-y: auto;
  padding: 1rem 0;
}

.sidebar-controls {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-top: 1px solid var(--border);
}

.theme-group {
  margin-bottom: 0.25rem;
}

.theme-header {
  display: flex;
  align-items: center;
  width: 100%;
  padding: 0.5rem 1rem;
  font-weight: 600;
  font-size: 0.875rem;
  text-align: left;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text);
  font-family: inherit;
  gap: 0.5rem;
}

.theme-header .chevron {
  flex-shrink: 0;
  transition: transform 0.2s ease;
}

.theme-header[aria-expanded="true"] .chevron {
  transform: rotate(90deg);
}

.theme-header[aria-expanded="false"] + .theme-pages {
  display: none;
}

.theme-pages {
  list-style: none;
  padding-left: 0;
}

.theme-pages a {
  display: block;
  padding: 0.35rem 1rem 0.35rem 2.25rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  border-left: 3px solid transparent;
  border-radius: 0 4px 4px 0;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.theme-pages a:hover {
  background: rgba(0, 0, 0, 0.04);
  color: var(--text);
}

[data-theme="dark"] .theme-pages a:hover {
  background: rgba(255, 255, 255, 0.04);
}

.theme-pages a.active {
  border-left-color: var(--accent);
  color: var(--accent);
  background: var(--accent-subtle);
  font-weight: 500;
}

/* ==========================================================================
   7. Main Content & Typography
   ========================================================================== */

.content {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem 2.5rem;
  width: 100%;
  min-width: 0;
}

.content h1 {
  font-family: var(--font-display);
  font-size: 2rem;
  margin-bottom: 1rem;
  font-weight: 700;
  line-height: 1.3;
}

.content h2 {
  font-family: var(--font-display);
  font-size: 1.5rem;
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  font-weight: 600;
  padding-bottom: 0.3rem;
  border-bottom: 1px solid var(--border);
  line-height: 1.4;
}

.content h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
  font-weight: 600;
  line-height: 1.4;
}

.content h4 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  margin-top: 1.25rem;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

.content h5 {
  font-family: var(--font-display);
  font-size: 1rem;
  margin-top: 1rem;
  margin-bottom: 0.5rem;
  font-weight: 600;
}

.content h6 {
  font-family: var(--font-display);
  font-size: 0.875rem;
  margin-top: 1rem;
  margin-bottom: 0.5rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.content p {
  margin-bottom: 1rem;
}

.content ul,
.content ol {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
}

.content li {
  margin-bottom: 0.25rem;
}

.content blockquote {
  border-left: 4px solid var(--accent);
  padding: 1rem;
  margin: 1rem 0;
  background: var(--surface);
  border-radius: 0 8px 8px 0;
}

.content blockquote p:last-child {
  margin-bottom: 0;
}

.content hr {
  border: none;
  height: 1px;
  background: var(--border);
  margin: 2rem 0;
}

.content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1rem;
}

.content th,
.content td {
  padding: 0.75rem;
  border: 1px solid var(--border);
  text-align: left;
}

.content th {
  background: var(--surface);
  font-weight: 600;
}

.content tr:nth-child(even) {
  background: rgba(0, 0, 0, 0.015);
}

[data-theme="dark"] .content tr:nth-child(even) {
  background: rgba(255, 255, 255, 0.02);
}

.content code {
  background: var(--code-bg);
  padding: 0.2em 0.4em;
  border-radius: 3px;
  font-size: 0.9em;
  font-family: 'SF Mono', SFMono-Regular, Consolas, 'Liberation Mono', Menlo, monospace;
}

.content pre {
  background: var(--code-bg);
  padding: 1rem;
  border-radius: 8px;
  overflow-x: auto;
  margin-bottom: 1rem;
}

.content pre code {
  padding: 0;
  background: none;
  font-size: 0.9em;
  line-height: 1.5;
}

.content img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08), 0 1px 3px rgba(0, 0, 0, 0.06);
  border: 1px solid var(--border);
  margin: 0.5rem 0;
}

[data-theme="dark"] .content img {
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.3), 0 1px 3px rgba(0, 0, 0, 0.2);
}

.content .video-embed {
  margin-bottom: 1rem;
}

.content .video-embed iframe {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: none;
  border-radius: 8px;
}

.content a {
  color: var(--accent);
  text-decoration: none;
}

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

/* ==========================================================================
   8. Heading Anchors
   ========================================================================== */

.heading-anchor {
  opacity: 0;
  text-decoration: none;
  color: var(--text-secondary);
  padding-left: 0.5rem;
  font-weight: 400;
  transition: opacity 0.2s;
}

.content h1:hover .heading-anchor,
.content h2:hover .heading-anchor,
.content h3:hover .heading-anchor,
.content h4:hover .heading-anchor,
.content h5:hover .heading-anchor,
.content h6:hover .heading-anchor {
  opacity: 1;
}

h1, h2, h3, h4, h5, h6 {
  scroll-margin-top: 80px;
}

/* ==========================================================================
   9. TOC Panel (Right Sidebar)
   ========================================================================== */

.toc {
  position: sticky;
  top: 80px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
  font-size: 0.875rem;
  padding: 2rem 1rem 2rem 0;
}

.toc ul {
  list-style: none;
  padding-left: 0;
}

.toc ul ul {
  padding-left: 0.75rem;
}

.toc a {
  color: var(--text-secondary);
  text-decoration: none;
  display: block;
  padding: 0.25rem 0.5rem;
  border-left: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}

.toc a:hover {
  color: var(--text);
}

.toc a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  font-weight: 500;
}

/* ==========================================================================
   10. Sidebar Controls (Language Switcher & Theme Toggle)
   ========================================================================== */

.lang-select {
  background: var(--bg);
  border: 1px solid var(--border);
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  color: var(--text);
  cursor: pointer;
  font-family: inherit;
  font-size: 0.875rem;
}

.lang-select:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
  cursor: pointer;
  padding: 0.4rem;
  color: var(--text-secondary);
  border-radius: 6px;
  transition: color 0.2s;
}

.theme-toggle:hover {
  color: var(--text);
}

.email-link {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.4rem;
  color: var(--text-secondary);
  border-radius: 6px;
  transition: color 0.2s;
}

.email-link:hover {
  color: var(--text);
}

/* ==========================================================================
   11. Search
   ========================================================================== */

.search-wrapper {
  position: relative;
}

.search-input {
  width: 250px;
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
  font-size: 0.875rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.search-input::placeholder {
  color: var(--text-secondary);
}

.search-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(217, 119, 6, 0.15);
}

[data-theme="dark"] .search-input:focus {
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.15);
}

.search-results {
  position: absolute;
  top: 100%;
  right: 0;
  width: 400px;
  max-height: 400px;
  overflow-y: auto;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.12);
  z-index: 200;
  margin-top: 0.5rem;
}

.search-results[hidden] {
  display: none;
}

.search-result-item {
  display: block;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  transition: background 0.15s;
  text-decoration: none;
  color: inherit;
}

.search-result-item:last-child {
  border-bottom: none;
}

.search-result-item:hover,
.search-result-item.selected {
  background: var(--surface);
}

.search-result-title {
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.15rem;
}

.search-result-theme {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 0.25rem;
}

.search-result-snippet {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

.search-result-snippet mark {
  background: var(--accent-subtle);
  color: var(--text);
  border-radius: 2px;
  padding: 0 2px;
}

mark.search-highlight {
  background: var(--accent-subtle);
  color: var(--text);
  border-radius: 2px;
  padding: 0 2px;
}

[data-theme="dark"] mark.search-highlight,
[data-theme="dark"] .search-result-snippet mark {
  background: rgba(245, 158, 11, 0.3);
}

/* ==========================================================================
   12. Responsive Breakpoints
   ========================================================================== */

/* Hide TOC on narrower screens */
@media (max-width: 1199px) {
  .toc {
    display: none;
  }

  .layout {
    grid-template-columns: 240px 1fr;
  }
}

/* Mobile: hide sidebar, single column */
@media (max-width: 991px) {
  .sidebar {
    display: none;
  }

  .layout {
    grid-template-columns: 1fr;
  }

  .hamburger {
    display: flex;
  }

  .search-input {
    display: none;
  }

  .search-toggle {
    display: flex;
  }

  .content {
    padding: 1.5rem 1rem;
  }
}

/* ==========================================================================
   13. Mobile Sidebar Overlay
   ========================================================================== */

.sidebar-backdrop[hidden] {
  display: none;
}

.sidebar-open .sidebar {
  display: flex;
  position: fixed;
  top: 60px;
  left: 0;
  bottom: 0;
  width: 280px;
  z-index: 150;
  background: var(--surface);
  transform: translateX(0);
  transition: transform 0.3s ease;
}

.sidebar-open .sidebar-backdrop {
  display: block;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 140;
}

/* ==========================================================================
   14. Mobile Search Overlay
   ========================================================================== */

.search-overlay-open .search-input {
  display: block;
  position: fixed;
  top: 60px;
  left: 0;
  right: 0;
  width: 100%;
  z-index: 160;
  border-radius: 0;
  border: none;
  border-bottom: 1px solid var(--border);
}

.search-overlay-open .search-results {
  position: fixed;
  top: calc(60px + 42px);
  left: 0;
  right: 0;
  width: 100%;
  border-radius: 0;
  border-left: none;
  border-right: none;
}

/* ==========================================================================
   15. Theme Toggle Icon Visibility
   ========================================================================== */

[data-theme="light"] .icon-moon {
  display: none;
}

[data-theme="dark"] .icon-sun {
  display: none;
}

/* ==========================================================================
   Utilities & Print
   ========================================================================== */

@media print {
  .header,
  .sidebar,
  .toc,
  .skip-link,
  .sidebar-backdrop {
    display: none;
  }

  .layout {
    display: block;
    padding-top: 0;
  }

  .content {
    max-width: 100%;
    padding: 0;
  }
}