APEX 5.0 Universal Theme Bug

The problem I described here is strange. In my case and I tested it on several laptops with many browsers and multiple installations, appears to be a Universal Theme related bug and occurs in some specific constellation - in my case on Windows 8.1 running FireFox or Google Chrome (IE11 works as expected). I noticed this problem while working on the Tabular Form chapter for the new Expert APEX book. The first thought I had is that I see pink elephants because the colleagues I asked to check the issue couldn't confirm it - they were using different OS. This seems to be somehow Windows 8.1 related by I am not 100% sure. Your help would be great and if you have the same problem, please join the post and provide your input.