body {
    font-family: Arial;
    background: #f2f2f2;
    margin: 0;
}
.center {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
.card {
    background: white;
    padding: 20px;
    max-width: 400px;
    margin: auto;
    border-radius: 8px;
}
input, select, button {
    width: 100%;
    padding: 10px;
    margin: 5px 0;
}
nav {
    background: #333;
    padding: 10px;
}
nav a {
    color: white;
    margin-right: 10px;
    text-decoration: none;
}
table {
    width: 100%;
}
@media (max-width: 600px) {
    .card {
        margin: 10px;
    }
}