You can do this on hover (aka mouseover) with Pure CSS.
CSS Disjointed Image Rollovers (tooltips)
but is there a way to simulate onClick with CSS? (sorry, I'm a relative newbie with all of this)
but is there a way to simulate onClick with CSS?
Actually there is but it only works on touch screen devices like iPhone, iPad and Droid.
If your visitors use a mouse operated device, they will see the event on hover.
If you must use onClick, look at the Show/Hide Layer tutorial below.
Thank you - I will use that.