i want to use http://www.webcredible.co.uk/user-friendly-resources/css/rollover-buttons.shtml for buttons but im concern a bit because it uses css hidden / visibility , to hide an img when mouse is out of the hitzone of img
if you run the site through certain online html / css validators / accessibility checkers, a few online tools will show results of "hidden text" if the css states "display:none", or similar, if the text doesn't include premium keyword phrases and everything else about the site is G friendly, it shouldn't matter....