/* ===== Reset & Base ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg: #f8f9fa;
  --color-surface: #ffffff;
  --color-border: #e1e4e8;
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #eff6ff;
  --color-text: #1f2937;
  --color-text-muted: #6b7280;
  --color-heading: #111827;
  --color-tag-bg: #e0e7ff;
  --color-tag-text: #3730a3;
  --sidebar-width: 260px;
  --header-height: 60px;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --transition: 0.2s ease;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

/* ===== Site Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 1rem;
}

.site-header .logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-heading);
  white-space: nowrap;
}

.site-header .logo a {
  color: inherit;
}

.site-header .logo a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

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

.site-header nav a {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  padding: 0.3rem 0.6rem;
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
}

.site-header nav a:hover {
  background: var(--color-primary-light);
  color: var(--color-primary);
  text-decoration: none;
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.4rem;
  color: var(--color-text);
}

/* ===== Layout ===== */
.site-wrapper {
  display: flex;
  min-height: calc(100vh - var(--header-height));
}

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  background: var(--color-surface);
  border-right: 1px solid var(--color-border);
  padding: 1.5rem 1rem;
  position: sticky;
  top: var(--header-height);
  height: calc(100vh - var(--header-height));
  overflow-y: auto;
}

.sidebar-title {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  padding: 0 0.5rem;
  margin-bottom: 0.5rem;
}

.sidebar ul {
  list-style: none;
}

.sidebar ul li + li {
  margin-top: 0.1rem;
}

.sidebar-category {
  margin-top: 1rem;
}

.sidebar-category-title {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.3rem 0.5rem;
  margin-bottom: 0.2rem;
}

.sidebar a {
  display: block;
  font-size: 0.875rem;
  color: var(--color-text);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
}

.sidebar a:hover,
.sidebar a.active {
  background: var(--color-primary-light);
  color: var(--color-primary);
  text-decoration: none;
}

/* ===== Main Content ===== */
.main-content {
  flex: 1;
  padding: 2rem 2.5rem;
  max-width: 900px;
}

/* ===== Hero (homepage) ===== */
.hero {
  text-align: center;
  padding: 3rem 1rem 2rem;
}

.hero h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-heading);
  margin-bottom: 0.75rem;
}

.hero p {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  max-width: 520px;
  margin: 0 auto 1.5rem;
}

/* ===== Category Grid ===== */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}

.category-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  transition: box-shadow var(--transition), transform var(--transition);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.category-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.category-card .card-icon {
  font-size: 2rem;
  line-height: 1;
}

.category-card h2 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-heading);
}

.category-card p {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  flex: 1;
}

.category-card .card-link {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-top: 0.25rem;
}

.category-card .card-link:hover {
  text-decoration: underline;
}

.category-card .doc-count {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

/* ===== Document List ===== */
.doc-list {
  list-style: none;
  margin-top: 1rem;
}

.doc-list li {
  border-bottom: 1px solid var(--color-border);
}

.doc-list li:first-child {
  border-top: 1px solid var(--color-border);
}

.doc-list a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 0.5rem;
  color: var(--color-text);
  font-size: 0.95rem;
  transition: color var(--transition);
}

.doc-list a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.doc-list .doc-icon {
  font-size: 1.1rem;
  flex-shrink: 0;
}

.doc-list .doc-title {
  font-weight: 500;
  flex: 1;
}

.doc-list a:hover .doc-title {
  text-decoration: underline;
}

/* ===== Page Header ===== */
.page-header {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.page-header .breadcrumb {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

.page-header .breadcrumb a {
  color: var(--color-text-muted);
}

.page-header .breadcrumb a:hover {
  color: var(--color-primary);
}

.page-header h1 {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--color-heading);
  margin-bottom: 0.5rem;
}

.page-header .page-meta {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

/* ===== Tags ===== */
.tag {
  display: inline-block;
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.15rem 0.6rem;
  border-radius: 999px;
}

/* ===== Article Content ===== */
.article-content h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-heading);
  margin: 2rem 0 0.75rem;
  padding-top: 0.5rem;
}

.article-content h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-heading);
  margin: 1.5rem 0 0.5rem;
}

.article-content p {
  margin-bottom: 1rem;
  color: var(--color-text);
}

.article-content ul,
.article-content ol {
  margin: 0.5rem 0 1rem 1.5rem;
}

.article-content li {
  margin-bottom: 0.4rem;
}

.article-content pre {
  background: #1e1e2e;
  color: #cdd6f4;
  padding: 1rem 1.25rem;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 1rem 0;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  line-height: 1.6;
}

.article-content code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: #f3f4f6;
  padding: 0.15em 0.4em;
  border-radius: 4px;
  color: #be185d;
}

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

.article-content blockquote {
  border-left: 4px solid var(--color-primary);
  padding: 0.5rem 1rem;
  margin: 1rem 0;
  background: var(--color-primary-light);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--color-text);
}

.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.9rem;
}

.article-content th,
.article-content td {
  border: 1px solid var(--color-border);
  padding: 0.6rem 0.9rem;
  text-align: left;
}

.article-content th {
  background: var(--color-bg);
  font-weight: 600;
  color: var(--color-heading);
}

.article-content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 2rem 0;
}

/* ===== In-page TOC ===== */
.toc-box {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  font-size: 0.875rem;
}

.toc-box .toc-title {
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 0.5rem;
}

.toc-box ol {
  margin-left: 1.25rem;
}

.toc-box li {
  margin-bottom: 0.25rem;
}

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--color-border);
  text-align: center;
  padding: 1.5rem;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  background: var(--color-surface);
}

/* ===== Search Bar ===== */
.search-bar {
  position: relative;
  max-width: 360px;
  margin: 0 auto 2rem;
}

.search-bar input {
  width: 100%;
  padding: 0.6rem 1rem 0.6rem 2.4rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 0.9rem;
  background: var(--color-surface);
  color: var(--color-text);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.search-bar input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.search-bar .search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--color-text-muted);
  pointer-events: none;
}

/* ===== Nav Pills ===== */
.nav-pills {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.nav-pills a {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-muted);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  transition: all var(--transition);
}

.nav-pills a:hover,
.nav-pills a.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
  text-decoration: none;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    left: -100%;
    top: var(--header-height);
    height: calc(100vh - var(--header-height));
    z-index: 90;
    transition: left var(--transition);
    box-shadow: var(--shadow-md);
  }

  .sidebar.open {
    left: 0;
  }

  .menu-toggle {
    display: block;
  }

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

  .hero h1 {
    font-size: 1.75rem;
  }

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