gistfile1.css

.bg-full-screen {
    background-image: url(...);
    background-color: transparent;
    background-size: cover;
    background-position: center center;
    background-repeat: no-repeat;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    min-height: 800px;
}