Answer by Sandro Paganotti for CSS text-indent - remove text but not content added using :after

You can try something like this: http://jsfiddle.net/sandro_paganotti/HupTL/

div{
    position: relative;
    text-indent: -9000px;
}
div:after{
    content: 'hi!';
    display: block;
    position: absolute;
    text-indent: 0;
    top:0;
    left:0;
    right:0;
    bottom:0;
}