Some CSS styles need to be applied to an element on hover, and CSS styles have to be applied using javascript/jquery directly and not through stylesheets or $(this).ad
$(this).ad
I find using mouseenter and mouseleave to be better than hover. There's more control.
$("#somecontent").mouseenter(function() { $(this).css("background", "#F00").css("border-radius", "3px"); }).mouseleave(function() { $(this).css("background", "00F").css("border-radius", "0px"); });