body {
    font-family: Arial, sans-serif;
    background-color: #222;
    color: #fff;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}
.login-box {
    background: #333;
    padding: 20px;
    border-radius: 5px;
    width: 300px;
}
input, button {
    width: 100%;
    margin-top: 10px;
    padding: 8px;
    border: none;
    border-radius: 3px;
}
button {
    background: #5cb85c;
    color: white;
    cursor: pointer;
}
.error {
    color: #f00;
}