:root { --ab-primary: #1a5f7a; --ab-secondary: #159895; --ab-light: #f8f9fa; --ab-dark: #2c3e50; }
body { font-family: 'Segoe UI', Roboto, sans-serif; background-color: var(--ab-light); }
.sidebar { width: 260px; height: 100vh; position: fixed; top: 0; left: 0; background: linear-gradient(180deg, var(--ab-dark), var(--ab-primary)); padding-top: 20px; color: white; z-index: 1000; }
.sidebar a { color: rgba(255,255,255,0.8); text-decoration: none; padding: 12px 20px; display: block; margin: 5px 10px; border-radius: 5px; }
.sidebar a:hover, .sidebar a.active { background-color: var(--ab-secondary); color: white; }
.main-content { margin-left: 260px; padding: 20px; }
.stats-card { border: none; border-radius: 10px; box-shadow: 0 4px 6px rgba(0,0,0,0.05); }