Photo Gallery Forums

Is there any way to influence the background color of a button when hovering above it in the menu? For example at http://photoeye.ch a darkening effect is applied (from dark red to black), yet I can't seem to reproduce it in my gallery (using the 'softwhite' template, my buttons light up to a paler shade of grey - the effect I'm after is turning them deep grey on hover).

I'm sure there has to be a dependency to another configuration parameter, but I just can't seem to find it. A little help please? :)