retina-dom-to-image/spec/resources/css-bg/style.css

A fork of the dom-to-image library that outputs an image for higher DPI screens

#dom-node {
    width: 100px;
    height: 100px;
}
.with-background {
    background: url(/base/spec/resources/images/image.jpeg) no-repeat left top;
    background-size: 100px 100px;
    width: 100px;
    height: 100px;
}