body {
    background-image: url("/images/background.jpg");
}

.login-form {
    display: block;
    width: 480px;
    position: fixed;
    top: 50%;
    left: 50%;
    margin-top: -310px;
    margin-left: -210px;
}

.logo {
    width: 220px;
}

@media screen and ( max-height: 620px ) {
    .login-form {
        position: relative;
        width: 100%;
        top: 0;
        left: 0;
        margin: 0;
        height: 100vh;
    }
}