:root { --primary: #3498db; --bg: #f4f7f6; --text: #333; --card: #fff; }
.dark-mode { --primary: #9b59b6; --bg: #121212; --text: #e0e0e0; --card: #1e1e1e; }

body { font-family: 'Segoe UI', sans-serif; margin: 0; background: var(--bg); color: var(--text); transition: 0.3s; }
.sidebar { width: 220px; height: 100vh; background: var(--primary); color: white; position: fixed; padding: 20px; }
.sidebar a { color: white; text-decoration: none; display: block; padding: 10px 0; border-bottom: 1px solid rgba(255,255,255,0.1); }
.main { margin-left: 260px; padding: 40px; }
.card { background: var(--card); padding: 25px; border-radius: 12px; box-shadow: 0 4px 6px rgba(0,0,0,0.1); margin-bottom: 20px; }
.btn { background: var(--primary); color: white; border: none; padding: 10px 20px; border-radius: 5px; cursor: pointer; }
.btn:hover { opacity: 0.8; transform: translateY(-2px); }
input, select { padding: 10px; border-radius: 5px; border: 1px solid #ddd; width: 100%; max-width: 300px; margin-top: 5px; }