:root {
  --bg-color: #ffffff;
  --text-color: #1a1a1a;
  --text-muted: #666666;
  --border-color: #e0e0e0;
  --sidebar-bg: #f8f8f8;
  --accent-color: #0056b3;
  --code-bg: #f4f4f4;
  --pre-bg: #1a1a1a;
  --pre-text: #f4f4f4;
}

[data-theme='dark'] {
  --bg-color: #121212;
  --text-color: #e0e0e0;
  --text-muted: #a0a0a0;
  --border-color: #333333;
  --sidebar-bg: #1a1a1a;
  --accent-color: #4dabf7;
  --code-bg: #2a2a2a;
  --pre-bg: #000000;
  --pre-text: #e0e0e0;
}

body {
  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.5;
  color: var(--text-color);
  background-color: var(--bg-color);
  margin: 0;
  display: flex;
}

aside {
  width: 260px;
  height: 100vh;
  position: sticky;
  top: 0;
  background-color: var(--sidebar-bg);
  border-right: 1px solid var(--border-color);
  padding: 2rem 1rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
  max-width: 800px;
  padding: 2rem 4rem;
}

h1, h2, h3 {
  font-weight: 600;
  color: var(--text-color);
  margin-top: 1.5rem;
  margin-bottom: 0.75rem;
}

h1 { font-size: 2rem; margin-top: 0; border-bottom: 2px solid var(--border-color); padding-bottom: 0.5rem; }
h2 { font-size: 1.5rem; border-bottom: 1px solid var(--border-color); padding-bottom: 0.25rem; }

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

a:hover {
  text-decoration: underline;
}

nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

nav li {
  margin-bottom: 0.5rem;
}

.nav-link {
  display: block;
  padding: 0.35rem 0.75rem;
  color: var(--text-color);
  font-size: 0.9rem;
  text-decoration: none;
  border-radius: 4px;
}

.nav-link:hover {
  background-color: var(--border-color);
  text-decoration: none;
}

.nav-link.active {
  font-weight: 600;
  background-color: var(--border-color);
}

.nav-section-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
  padding-left: 0.75rem;
}

code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  background-color: var(--code-bg);
  padding: 0.15rem 0.3rem;
  border-radius: 3px;
  font-size: 0.875rem;
}

pre {
  background-color: var(--pre-bg);
  color: var(--pre-text);
  padding: 1rem;
  border-radius: 6px;
  overflow-x: auto;
}

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

.theme-toggle-btn {
  margin-top: auto;
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 0.5rem;
  cursor: pointer;
  font-size: 0.8rem;
  border-radius: 4px;
  text-align: center;
}

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

footer {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-color);
  font-size: 0.8rem;
  color: var(--text-muted);
}

@media (max-width: 768px) {
  body { flex-direction: column; }
  aside { width: 100%; height: auto; position: static; border-right: none; border-bottom: 1px solid var(--border-color); }
  main { padding: 2rem; }
}