:root {
  --sidebar-w: 260px;
  --accent: #0f6cbd;
  --accent-dark: #0a4a8f;
  --accent-light: #e6f2fc;
  --bg: #f7f9fc;
  --surface: #ffffff;
  --border: #dde3ea;
  --text: #1a2332;
  --text-muted: #5a6a7e;
  --code-bg: #1e2736;
  --code-text: #e8edf3;
  --radius: 6px;
  --shadow: 0 1px 4px rgba(0,0,0,0.08);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  font-size: 15px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  min-height: 100vh;
}

.sidebar {
  width: var(--sidebar-w);
  background: var(--code-bg);
  color: #c8d4e0;
  padding: 0;
  position: fixed;
  left: 0;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}
.sidebar-brand {
  background: var(--accent-dark);
  padding: 18px 20px;
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.5px;
  color: #fff;
  text-transform: uppercase;
}
.sidebar-brand span { display: block; font-size: 10px; font-weight: 400; opacity: 0.7; margin-top: 2px; letter-spacing: 0; text-transform: none; }
.sidebar-section { padding: 12px 20px 4px; font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: 1px; color: #6a849a; }
.sidebar a {
  display: block;
  padding: 7px 20px;
  color: #b0c4d8;
  text-decoration: none;
  font-size: 13.5px;
  border-left: 3px solid transparent;
  transition: all 0.15s;
}
.sidebar a:hover { color: #fff; background: rgba(255,255,255,0.06); }
.sidebar a.active { color: #fff; border-left-color: var(--accent); background: rgba(15,108,189,0.15); }

main {
  margin-left: var(--sidebar-w);
  max-width: 960px;
  padding: 40px 48px 80px;
}

.page-header {
  margin-bottom: 36px;
  padding-bottom: 20px;
  border-bottom: 2px solid var(--border);
}
.page-header .breadcrumb { font-size: 12px; color: var(--text-muted); margin-bottom: 8px; }
.page-header h1 { font-size: 28px; font-weight: 700; color: var(--text); line-height: 1.2; }
.page-header .subtitle { margin-top: 8px; color: var(--text-muted); font-size: 15px; }

h2 { font-size: 20px; font-weight: 700; margin: 36px 0 12px; color: var(--text); padding-bottom: 6px; border-bottom: 1px solid var(--border); }

p { margin-bottom: 14px; }

.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; margin: 20px 0; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  text-decoration: none;
  color: inherit;
  display: block;
  transition: box-shadow 0.15s, transform 0.15s;
}
.card:hover { box-shadow: 0 4px 16px rgba(0,0,0,0.12); transform: translateY(-2px); }
.card .card-icon { font-size: 28px; margin-bottom: 12px; }
.card h3 { margin: 0 0 8px; font-size: 16px; color: var(--accent); }
.card p { margin: 0 0 12px; font-size: 13px; color: var(--text-muted); line-height: 1.5; }
.card .card-links { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 4px; }
.card .card-links a {
  display: inline-block;
  font-size: 12px;
  color: var(--accent);
  background: var(--accent-light);
  border-radius: 10px;
  padding: 2px 10px;
  text-decoration: none;
  border-left: none;
  transition: background 0.15s;
}
.card .card-links a:hover { background: #c5dff7; color: var(--accent-dark); }

.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: #3a4f61; border-radius: 2px; }

/* Logo in sidebar */
.sidebar-logo {
  display: block;
  width: 120px;
  margin-bottom: 10px;
  opacity: 0.9;
}