body {
    font-family: Arial, sans-serif;
    background-color: #f2f2f2;
    padding: 30px;
}
.card {
    background: white;
    max-width: 600px;
    margin: auto;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.2);
}
ul {
    list-style: none;
    padding-left: 0;
}
li {
    margin-bottom: 10px;
    font-size: 1.1em;
}
a {
    text-decoration: none;
    color: #0077cc;
}
a:hover {
    text-decoration: underline;
}
.error {
    color: red;
    margin-top: 10px;
}
.login input[type="text"],
.login input[type="password"],
.login input[type="submit"] {
    width: 100%;
    padding: 8px;
    margin: 5px 0;
}

/* Para celdas vacías */
td.vacio {
    color: #999;
    font-style: italic;
    text-align: center;
}