body{font-family:system-ui;margin:0;background:#f1f5f9}
header{display:flex;align-items:center;gap:10px;padding:15px;background:#2563eb;color:white}
.menu{font-size:26px;cursor:pointer}
nav{position:fixed;top:0;left:-220px;width:200px;height:100%;background:#1e293b;padding:20px;transition:.3s}
nav a{display:block;color:white;text-decoration:none;margin:15px 0}
nav.active{left:0}
.content{padding:15px}
.card{background:white;padding:15px;border-radius:12px;margin:10px 0}
.alert{border-left:5px solid #f59e0b}
input,select,button{width:100%;padding:10px;margin:5px 0}
button{background:#16a34a;color:white;border:none;border-radius:8px}
.center{display:flex;align-items:center;justify-content:center;height:100vh}
.error{color:red}