I thought I'd head this issue off at the pass before anyone else noticed it.
The short version: Internet Explorer and Edge are not recommended for use with the new themes (Chameleon and Dashboard).
The slightly longer version: Chameleon and Dashboard use the latest CSS and browser technology to provide the best visual experience possible. In its time-honoured tradition of adhering to its own insular version of the Internet, Microsoft insists on doing things differently with their browsers, with the result that not all functions work with IE or Edge. In fact, while Edge is supported by the theme developer, IE is not officially supported for these reasons. If you do want to use the site with these browsers, I'd suggest switching to the default skin (4.2 Blue), which is much less resource-intensive. There are scrolling issues with the graphics-rich backgrounds with both Microsoft browsers (particularly IE, which will give you a bumpy ride with both themes but is a particular trainwreck with Dashboard).
In short, everything works fine with Firefox, Chrome, Opera and Vivaldi. Heck, even Avast! SafeZone browser plays nice with the code (if anyone even uses it ). Firefox is at the bottom of this list since you'll see some minor scrolling issues; all others mentioned perform flawlessly.