body {
    font-family: Arial, sans-serif;
    background: #111;
    color: #fff;
    padding: 2rem;
}
form {
    background: #222;
    padding: 2rem;
    border-radius: 8px;
    width: 300px;
    margin: 0 auto;
}
input, button {
    display: block;
    width: 100%;
    margin-bottom: 1rem;
}
.error {
    color: red;
}