What would be useful is an animated image that only animates when a visitor selects it. This would be very handy in instructional materials. This is fine as long as you don't accidentally make the color the same as the background . However, since each visitor can choose his or her browser's colors, there's no way to know if your color choices conflict. Likewise, don't redefine the colors of links.
People use the color of links to quickly identify a link's state.
If you redefine them, your site's visitors will have to work harder to read your pages. If it uses numeric HTML entities, there may be a problem. Verify that all the numeric entities have equivalent names. They may appear fine in your browser because you have a particular typeface, but others may not have it. Instead, they'll see garbage.