@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

:root {
  --bg-color: #f8fafc;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --surface: #ffffff;
  --border: #e2e8f0;
  --sidebar-width: 260px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;
}

/* Header */
header {
  display: flex;
  align-items: center;
  padding: 0 24px;
  height: 72px;
  background-color: var(--surface);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  box-shadow: 0 1px 2px rgba(0,0,0,0.02);
  justify-content: space-between;
}

.header-left {
  display: flex;
  align-items: center;
}

.menu-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 8px;
  border-radius: 8px;
  margin-right: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.2s;
}

.menu-btn:hover {
  background-color: var(--bg-color);
  color: var(--text-main);
}

.logo-container {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.logo-container img {
  height: 36px;
}

.logo-text {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.02em;
}

/* Layout */
.main-container {
  display: flex;
  flex: 1;
  overflow: hidden;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--surface);
  border-right: 1px solid var(--border);
  padding: 24px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: width 0.3s, opacity 0.3s;
  overflow-y: auto;
}

.nav-item {
  display: flex;
  align-items: center;
  padding: 10px 16px;
  text-decoration: none;
  color: var(--text-muted);
  font-weight: 500;
  border-radius: 8px;
  gap: 12px;
  transition: all 0.2s ease;
}

.nav-item:hover {
  background-color: var(--bg-color);
  color: var(--text-main);
}

.nav-item.active {
  background-color: #eff6ff;
  color: var(--primary);
}

.nav-item.active .nav-icon {
  fill: var(--primary);
}

.nav-icon {
  width: 20px;
  height: 20px;
  fill: var(--text-muted);
  transition: fill 0.2s;
}

/* Content */
.content {
  flex: 1;
  overflow-y: auto;
  padding: 48px 32px;
  scroll-behavior: smooth;
}

.content-inner {
  max-width: 800px;
  margin: 0 auto;
}

/* Hero */
.hero {
  text-align: center;
  margin-bottom: 56px;
}
.hero h1 {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
  color: var(--text-main);
}
.hero p {
  font-size: 1.25rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto;
}
.hero img {
  max-width: 120px;
  margin-bottom: 24px;
}

/* Sections */
section {
  background-color: var(--surface);
  border-radius: 16px;
  padding: 40px;
  margin-bottom: 32px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
  border: 1px solid rgba(0,0,0,0.02);
}

h2 {
  font-size: 1.75rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-top: 0;
  margin-bottom: 24px;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 12px;
}

h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 32px;
  margin-bottom: 16px;
}

p, li {
  line-height: 1.7;
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-bottom: 16px;
}

ul {
  padding-left: 24px;
}

li {
  margin-bottom: 8px;
}

a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 500;
}
a:hover {
  text-decoration: underline;
}

.img-fluid {
  max-width: 100%;
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  margin: 24px 0;
}

/* Feature Grid */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
  margin-top: 32px;
}

.feature-box {
  background-color: var(--bg-color);
  border-radius: 12px;
  padding: 24px;
  border: 1px solid var(--border);
}

.feature-box h3 {
  margin-top: 0;
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-main);
}

/* Code */
code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  background-color: var(--bg-color);
  color: #c53030;
  padding: 2px 6px;
  border-radius: 6px;
  font-size: 0.9em;
  border: 1px solid var(--border);
}

pre {
  background-color: #0f172a;
  padding: 20px;
  border-radius: 12px;
  overflow-x: auto;
  margin: 24px 0;
}

pre code {
  background-color: transparent;
  color: #e2e8f0;
  border: none;
  padding: 0;
  font-size: 0.95em;
}

/* Details/Summary */
details {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 16px;
  overflow: hidden;
}

summary {
  padding: 16px;
  cursor: pointer;
  font-weight: 600;
  background-color: var(--bg-color);
  color: var(--text-main);
}

summary:hover {
  background-color: #f1f5f9;
}

details p, details pre {
  margin: 16px;
}

/* Links & Buttons */
.github-link {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s;
}

.github-link:hover {
  color: var(--text-main);
  text-decoration: none;
}

.hero-actions {
  margin-top: 32px;
  display: flex;
  justify-content: center;
  gap: 16px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  border-radius: 8px;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.2s;
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  color: #ffffff;
  text-decoration: none;
}

.btn-secondary {
  background-color: var(--surface);
  color: var(--text-main);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background-color: var(--bg-color);
  text-decoration: none;
}

/* Scrollbar */
*::-webkit-scrollbar {
  height: 12px;
  width: 12px;
}
*::-webkit-scrollbar-track {
  background: transparent;
}
*::-webkit-scrollbar-thumb {
  background-color: rgba(148, 163, 184, 0.4);
  border-radius: 6px;
  border: 3px solid var(--bg-color);
}
*::-webkit-scrollbar-thumb:hover {
  background-color: rgba(148, 163, 184, 0.6);
}

@media (max-width: 768px) {
  .sidebar {
    position: absolute;
    height: calc(100vh - 72px);
    z-index: 100;
    box-shadow: 4px 0 16px rgba(0,0,0,0.05);
  }
  section {
    padding: 24px;
  }
  .content {
    padding: 24px 16px;
  }
}