_jumbotron.scss

/*
    This requires the containing element to have
        position:   relative;
    set.
*/

img.bg-jumbotron {
    position:   absolute;
    left:       0;
    right:      0;
    top:        0;    
    bottom:     0;
    width:      100%;
    height:     100%;
    object-fit: cover;
}