body{font-family:Arial, Helvetica, sans-serif; padding:15px}
nav a{margin-right:8px}
.card{max-width:420px;margin:40px auto;padding:20px;border:1px solid #ddd;border-radius:6px}
.error{color:#b00}
table{border-collapse:collapse;width:100%}
th,td{border:1px solid #ccc;padding:6px}