header.masthead {
    position: relative;
    overflow: hidden;
}

header.masthead div.container {
    position: relative;
    z-index: 2;
}

header.masthead img.background {
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: auto;
    min-height: 100%;
    opacity: 0.6;
}