found the solution - in Firefox it is the option under tools> advanced> UNCHECK "use hardware acceleration" option - when I unchecked this the problems went away!
another strange example with firefox is when site use other fonts for content. At my computer some sites are different in firefox and in browsers like chrome and safari and ie are same style
I've seen this for some time - IE uses some advanced OS / Browser features to make the fonts look better and the others in general render slightly different in appearance
I've also seen where a client does not have the standard web friendly font(s) installed on the computer OR they have the ZOOM accidently set to a higher or lower value OR they have a forced font in their settings that overides the site CSS but none of the above are caused by DHE ...
> another strange example with firefox is when site use other fonts for content. At my computer some sites are different in firefox and in browsers like chrome and safari and ie are same style