:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --bg-card: #161f2c;
  --border-color: #30363d;
  --text-primary: #f0f6fc;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent-cyan: #00e5ff;
  --accent-green: #00e676;
  --accent-amber: #ffd600;
  --accent-red: #ff5252;
  --accent-blue: #58a6ff;
  --sidebar-width: 280px;
  --header-height: 64px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans", Helvetica, Arial, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

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

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent-cyan);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: #80f0ff;
  text-decoration: underline;
}

/* Header & Top Bar */
.top-nav {
  position: sticky;
  top: 0;
  height: var(--header-height);
  background-color: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  z-index: 100;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: -0.5px;
  color: var(--text-primary);
}

.brand .badge {
  background: rgba(0, 229, 255, 0.15);
  color: var(--accent-cyan);
  border: 1px solid rgba(0, 229, 255, 0.4);
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-family: var(--font-mono);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 20px;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
}

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

.btn-github {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: background 0.2s ease, border-color 0.2s ease;
}

.btn-github:hover {
  background: #30363d;
  border-color: #8b949e;
  text-decoration: none;
}

/* Layout */
.layout-container {
  display: flex;
  min-height: calc(100vh - var(--header-height));
  max-width: 1440px;
  margin: 0 auto;
}

/* Sidebar Navigation */
.sidebar {
  width: var(--sidebar-width);
  position: sticky;
  top: var(--header-height);
  height: calc(100vh - var(--header-height));
  overflow-y: auto;
  border-right: 1px solid var(--border-color);
  padding: 24px 16px;
  flex-shrink: 0;
}

.sidebar-group {
  margin-bottom: 24px;
}

.sidebar-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-muted);
  margin-bottom: 8px;
  padding: 0 12px;
}

.sidebar-menu {
  list-style: none;
}

.sidebar-menu li a {
  display: block;
  padding: 6px 12px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  border-radius: 6px;
  transition: all 0.15s ease;
}

.sidebar-menu li a:hover {
  color: var(--text-primary);
  background-color: rgba(255, 255, 255, 0.05);
  text-decoration: none;
}

.sidebar-menu li a.active {
  color: var(--accent-cyan);
  background-color: rgba(0, 229, 255, 0.1);
  font-weight: 600;
}

/* Main Content Area */
.content {
  flex: 1;
  padding: 40px 48px 80px 48px;
  max-width: 900px;
}

.content h1 {
  font-size: 2.4rem;
  font-weight: 800;
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.content h2 {
  font-size: 1.7rem;
  font-weight: 700;
  margin: 48px 0 16px 0;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
  letter-spacing: -0.5px;
}

.content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 28px 0 12px 0;
  color: var(--text-primary);
}

.content p {
  margin-bottom: 16px;
  color: #c9d1d9;
}

.content ul, .content ol {
  margin-bottom: 16px;
  padding-left: 24px;
  color: #c9d1d9;
}

.content li {
  margin-bottom: 6px;
}

/* Visual Media Container */
.media-showcase {
  margin: 24px 0;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border-color);
  background: #010409;
}

.media-showcase img {
  width: 100%;
  display: block;
}

.media-caption {
  padding: 10px 16px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-color);
  background: var(--bg-secondary);
}

/* Callout Alert Boxes */
.callout {
  padding: 16px 20px;
  margin: 20px 0;
  border-radius: 8px;
  border-left: 4px solid var(--accent-cyan);
  background: rgba(0, 229, 255, 0.05);
}

.callout.callout-warning {
  border-left-color: var(--accent-amber);
  background: rgba(255, 214, 0, 0.05);
}

.callout.callout-danger {
  border-left-color: var(--accent-red);
  background: rgba(255, 82, 82, 0.05);
}

.callout-title {
  font-weight: 700;
  margin-bottom: 4px;
  color: var(--text-primary);
}

/* Code Snippets */
pre {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 16px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.45;
  margin: 16px 0;
}

code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background-color: rgba(110, 118, 129, 0.2);
  padding: 2px 6px;
  border-radius: 4px;
}

pre code {
  background: transparent;
  padding: 0;
}

/* Keyboards & Badges */
kbd {
  display: inline-block;
  padding: 3px 6px;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1;
  color: var(--text-primary);
  vertical-align: middle;
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  box-shadow: inset 0 -1px 0 var(--border-color);
}

/* Data Tables */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: 0.95rem;
}

th, td {
  padding: 12px 16px;
  border: 1px solid var(--border-color);
  text-align: left;
}

th {
  background-color: var(--bg-secondary);
  font-weight: 600;
  color: var(--text-primary);
}

tr:nth-child(even) {
  background-color: rgba(255, 255, 255, 0.02);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border-color);
  padding: 32px 24px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Responsive Navigation */
@media (max-width: 900px) {
  .sidebar {
    display: none;
  }
  .content {
    padding: 24px 20px;
  }
}