* { box-sizing: border-box; }
body { font-family: system-ui, Arial, sans-serif; margin: 0; background: #f4f6f8; color: #222; }
.contenedor { max-width: 960px; margin: 24px auto; padding: 0 16px; }
.tarjeta { background: #fff; border: 1px solid #e2e6ea; border-radius: 8px; padding: 20px; }
.campo { margin-bottom: 12px; }
.campo label { display: block; font-size: 14px; margin-bottom: 4px; }
.campo input, .campo select { width: 100%; padding: 8px; border: 1px solid #ccc; border-radius: 4px; }
.btn { background: #2563eb; color: #fff; border: 0; padding: 9px 16px; border-radius: 4px; cursor: pointer; text-decoration: none; display: inline-block; }
.btn.gris { background: #6b7280; }
.error { background: #fee2e2; color: #991b1b; padding: 8px 12px; border-radius: 4px; margin-bottom: 12px; }
.ok { background: #dcfce7; color: #166534; padding: 8px 12px; border-radius: 4px; margin-bottom: 12px; }
table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 8px; border-bottom: 1px solid #eee; }
nav a { margin-right: 14px; }