header:not(.top-header) {
    background-image: url('/themes/_system/bootstrap4/css/templates/images/christmas.png');
    background-position: center right;
    background-repeat: no-repeat;
    background-size: auto 100%;
}

.main-slider {
    background-image: url('/themes/_system/bootstrap4/css/templates/images/christmas_back.jpg');
}