Most of the answers and suggestions in the older post on SO you reffered to try to manipulate the DOM by adding spans or divs for each line. But that's actually not a waterproof approach since it is not cross- browser compatble, especially not with mobile browsers. You should use a dynamically jquery controlled div that jumps behind the lines. The div should be dynamically be positioned with a jquery function triggered on mousemove calculating the div jumping on line-height depending on mouse cursor position
