body {
    font-family: Arial, sans-serif;
    margin: 20px;
    background: #f5f5f5;
}
nav a {
    margin-right: 10px;
    text-decoration: none;
    color: #333;
}
nav a:hover {
    text-decoration: underline;
}
.container {
    background: #fff;
    padding: 20px;
    border-radius: 4px;
}
table {
    width: 100%;
    border-collapse: collapse;
}
th, td {
    padding: 8px;
    border: 1px solid #ccc;
}
.error {
    color: red;
}