How to rotate the background image in the container?

Very well done and answered here – http://www.sitepoint.com/css3-transform-background-image/

#myelement:before {
    content: "";
    position: absolute;
    width: 200%;
    height: 200%;
    top: -50%;
    left: -50%;
    z-index: -1;
    background: url(background.png) 0 0 repeat;
    transform: rotate(30deg);
}