OK, thanks, if CSS is recommended practice, then obviously that's the way to go (in addition to being easier to understand). My experience with CSS is fairly limited, so I fiddled around a bit and tried to come up with a procedure.
First, I defined a div class by adding the following to the CSS for the vector skin:
/* CSS experiment: image shown on hover */
div.hoverbox :hover {
image: url(//upload.wikimedia.org/wikipedia/mediawiki/a/a3/EasyLogicsubset.png);
border: 2px;
font-size: 120%;
}
(or alternatively, #hoverbox :hover )
Second, I tried to apply this by placing div tags around the file:
<div class="hoverbox">[[File:EasyLogicpsubset.png]]</div>
(or alternatively, "div id=" )
Unfortunately, that doesn't work, so where did I go wrong?