Depends what you mean by highlight. I'm pretty sure you can just add an event listener for mouseover on whichever image you want to highlight. Once that is triggered then have Javascript give the CSS the value of box-shadow:________ (whatever properties you want). If you wanted to highlight then you most likely would pick a bright color (like yellow).
It's excellent for making stuff look aesthetically pleasing. More info:
http://www.w3schools.com/cssref/css3_pr_box-shadow.asp