how to cover iframe with image code example

Example: iframe on top of image

.outer {
    background-image: url('http://i.stack.imgur.com/6hnLq.png');
    width:420px;
    height:365px;
}
.inner {
    position: relative;
    background-color:;
    left: 67px;
    top: 109px;
    width:277px;
    height:150px;
}