:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-sidebar: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --border: #e2e8f0;
  --code-bg: #f1f5f9;
  --header-height: 64px;
  --sidebar-width: 280px;
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-sidebar: #0f172a;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --border: #334155;
  --code-bg: #1e293b;
}

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

body {
  font-family: 'Outfit', 'Inter', system-ui, -apple-system, sans-serif;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color 0.3s, color 0.3s;
}

/* Layout */
.app-container {
  display: flex;
  min-height: 100vh;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  position: fixed;
  height: 100vh;
  overflow-y: auto;
  transition: transform 0.3s;
  z-index: 50;
}

.sidebar-header {
  height: var(--header-height);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  border-bottom: 1px solid var(--border);
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--accent);
}

.nav-links {
  padding: 1.5rem 0;
  list-style: none;
}

.nav-item {
  padding: 0.5rem 1.5rem;
}

.nav-link {
  display: block;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color 0.2s;
  cursor: pointer;
}

.nav-link:hover,
.nav-link.active {
  color: var(--accent);
  font-weight: 500;
}

.nav-section {
  margin-top: 1.5rem;
  padding: 0 1.5rem;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  opacity: 0.7;
  font-weight: 600;
}

/* Main Content */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
}

/* Header */
.top-header {
  height: var(--header-height);
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: flex-end;
  align-items: center;
  padding: 0 2rem;
  position: sticky;
  top: 0;
  z-index: 40;
}

.controls {
  display: flex;
  gap: 1rem;
  align-items: center;
}

.btn-icon {
  background: none;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  padding: 0.5rem;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.btn-icon:hover {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
}

.lang-switch {
  display: flex;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  overflow: hidden;
}

.lang-btn {
  background: none;
  border: none;
  padding: 0.5rem 0.75rem;
  cursor: pointer;
  font-size: 0.875rem;
  color: var(--text-secondary);
  transition: all 0.2s;
}

.lang-btn.active {
  background-color: var(--accent);
  color: white;
}

/* Content Area */
.content-area {
  padding: 3rem;
  max-width: 900px;
  margin: 0 auto;
  width: 100%;
}

section {
  margin-bottom: 4rem;
  scroll-margin-top: calc(var(--header-height) + 2rem);
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
  line-height: 1.2;
}

h2 {
  font-size: 1.8rem;
  margin: 2.5rem 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

h3 {
  font-size: 1.4rem;
  margin: 2rem 0 1rem;
}

p,
li {
  margin-bottom: 1rem;
  color: var(--text-secondary);
}

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

code {
  background-color: var(--code-bg);
  padding: 0.2rem 0.4rem;
  border-radius: 0.25rem;
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.9em;
  color: var(--accent);
}

pre {
  background-color: var(--code-bg);
  padding: 1.5rem;
  border-radius: 0.5rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  border: 1px solid var(--border);
}

pre code {
  background-color: transparent;
  padding: 0;
  color: inherit;
  font-size: 0.9rem;
}

.mermaid {
  background-color: white;
  padding: 2rem;
  border-radius: 0.5rem;
  margin-bottom: 2rem;
  text-align: center;
  border: 1px solid var(--border);
}

[data-theme="dark"] .mermaid {
  background-color: #e2e8f0;
  /* Keeping mermaid light for visibility, or customize */
}

/* Responsive */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
  }

  .content-area {
    padding: 1.5rem;
  }

  .mobile-menu-btn {
    display: block;
    margin-right: auto;
  }
}

.hidden {
  display: none !important;
}