body {
    background-image: url(../img/bg-login.jpg);
    background-size: cover;
}
.site-login {
    width: 500px;
    top: 50%;
    height: auto;
    text-align: center;
    left: 50%;
    margin-top: -165px;
    margin-left: -250px;
    position: absolute;
    background-color: rgba(255, 255, 255, 0.8);
    border-radius: 10px;
    padding: 20px;
}
.site-login h1 {
    margin-bottom: 20px;
    font-weight: bold;
    color: #555;
}
.form-control, .site-login .btn-primary {
    margin: 0 auto;
    width: 300px;
    text-align: center;
    height: 42px;
    font-size: 18px;
    }