:root {
  /* Colors */
  --text-primary: #1a1a1a;
  --text-secondary: #495057;
  --text-muted: #666;
  --heading-primary: #2c3e50;
  --heading-secondary: #34495e;
  --link-color: cornflowerblue;
  --border-color: #e9ecef;
  --bg-light: #f8f9fa;
  --bg-primary: #fff;
  --nav-bg: #f8f9fa;

  /* Shadows */
  --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
}

* {
  box-sizing: border-box;
}

body {
  font-family: system-ui, -apple-system, sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 0;
  color: var(--text-primary);
  background: var(--bg-primary);
}

.main-container {
  display: flex;
  min-height: 100vh;
}

.side-nav {
  width: 250px;
  flex-shrink: 0;
  background: var(--nav-bg);
  border-right: 1px solid var(--border-color);
  padding: 2rem;
}

.side-nav-inner {
  position: sticky;
  top: 2rem;
}

.site-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--heading-primary);
  text-decoration: none;
  display: block;
  margin-bottom: 2rem;
}

.site-title:hover {
  color: var(--link-color);
}

main {
  flex: 1;
  max-width: 800px;
  padding: 2rem 3rem;
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  margin-top: 0;
  color: var(--heading-primary);
  font-weight: 500;
  font-family: Montserrat, system-ui, -apple-system, sans-serif;
}

h2 {
  font-size: 1.8rem;
  margin-top: 2rem;
  color: var(--heading-secondary);
  border-bottom: 2px solid var(--border-color);
  padding-bottom: 0.5rem;
}

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

a:hover {
  text-decoration: underline;
}

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

nav ul li {
  margin-bottom: 0.5rem;
}

nav .nav-link {
  display: block;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  color: var(--text-secondary);
  transition: background-color 0.2s;
}

nav .nav-link:hover {
  background: rgba(0, 0, 0, 0.05);
  text-decoration: none;
}

nav .nav-link.active {
  background: var(--link-color);
  color: white;
}

footer {
  text-align: center;
  padding: 2rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
}

/* Breadcrumbs */
.breadcrumbs {
  margin-bottom: 2rem;
  font-size: 0.9rem;
}

.breadcrumbs ol {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
}

.breadcrumbs li {
  display: flex;
  align-items: center;
}

.breadcrumbs li:not(:last-child)::after {
  content: "/";
  margin: 0 0.5rem;
  color: var(--text-muted);
}

.breadcrumbs a {
  color: var(--link-color);
}

.breadcrumbs [aria-current="page"] {
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 900px) {
  .main-container {
    flex-direction: column;
  }

  .side-nav {
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border-color);
    padding: 1rem;
  }

  .side-nav-inner {
    position: static;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 1rem;
  }

  .site-title {
    margin-bottom: 0;
  }

  nav ul {
    display: flex;
    gap: 0.5rem;
  }

  nav ul li {
    margin-bottom: 0;
  }

  main {
    padding: 1.5rem;
  }

  h1 {
    font-size: 2rem;
  }
}