:after hack to apply background-color above background-image without extra markup

bg-color>bg-image.css

header:after {
    background-color: rgba(0, 0, 0, 0.3);
    content: "";
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
    z-index: -1;
}

header {
    background-image: url(foo.png);
    position: relative;
    z-index: 1;
}