Found this while I was jerking around on the pirated Sonic Adventure.

It looks like all Planet Web configs are written in HTML.
My browser can't find these picts because it doesnt found on that url.
There are more pages, but I didn't looked it. Like send mail etc
EDIT: I Quick checked the Compose mail pages and its the only one where I saw colours.
More screenshots tomorrow.

 

Yep, this is how all of those custom browser discs that are floating around the internet are made.