body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}
header {
    background-color: #333;
    color: white;
    padding: 10px 20px;
    text-align: center;
}
nav a {
    color: white;
    margin: 0 10px;
    text-decoration: none;
}
main {
    padding: 20px;
}
form {
    max-width: 400px;
    margin: 0 auto;
    background: white;
    padding: 20px;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}
form label, form input, form button {
    display: block;
    width: 100%;
    margin-bottom: 10px;
}
form button {
    background-color: #333;
    color: white;
    border: none;
    padding: 10px;
    cursor: pointer;
}
#login-message, #upload-message {
    text-align: center;
    margin-top: 10px;
    color: red;
}