#login-overlay {
    position: absolute;
    width: 100%;
    height: 100%;
    background: {{background-gradient}}
    background-size: 400% 400%;
    -webkit-animation: Gradient 15s ease infinite;
    -moz-animation: Gradient 15s ease infinite;
    animation: Gradient 15s ease infinite;
}

@-webkit-keyframes Gradient {
    0% {
        background-position: 0% 50%
    }
    50% {
        background-position: 100% 50%
    }
    100% {
        background-position: 0% 50%
    }
}

@-moz-keyframes Gradient {
    0% {
        background-position: 0% 50%
    }
    50% {
        background-position: 100% 50%
    }
    100% {
        background-position: 0% 50%
    }
}

@keyframes Gradient {
    0% {
        background-position: 0% 50%
    }
    50% {
        background-position: 100% 50%
    }
    100% {
        background-position: 0% 50%
    }
}