*{box-sizing:border-box}body{font-family:Arial,sans-serif;margin:0;background:#f4f6f8;color:#222}
header{background:#263238;color:white;padding:22px;text-align:center}nav{display:flex;flex-wrap:wrap;justify-content:center;background:#37474f}
nav a{color:white;text-decoration:none;padding:14px 18px}nav a:hover{background:#546e7a}
main{max-width:1100px;margin:28px auto;background:white;padding:25px;border-radius:8px;box-shadow:0 2px 8px #bbb}
table{width:100%;border-collapse:collapse;font-size:14px}th,td{border:1px solid #ccc;padding:8px;text-align:left}th{background:#eceff1}
input,select{width:100%;padding:9px;margin:6px 0 14px;border:1px solid #aaa;border-radius:4px}
button,.boton{display:inline-block;background:#37474f;color:white;border:0;padding:10px 16px;border-radius:4px;text-decoration:none;cursor:pointer}
.peligro{background:#b71c1c}.mensaje{padding:12px;background:#e8f5e9;margin:15px 0}.error{background:#ffebee}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:15px}.card{padding:20px;background:#eceff1;border-radius:7px;text-align:center}
@media(max-width:600px){nav{flex-direction:column;text-align:center}main{margin:12px;padding:15px}table{font-size:11px}}