That is because the site does not correctly handle the situation where the user has white text set. For some, using the iefix.reg file included inside the Program Files\Stardock\Object Desktop\WindowBlinds\Blackcomb directory (double-click it) will help, but if it does not, your main method of recourse would be to complain to the site admins, because they should not be relying on the text colour being a certain colour. Usually it is a simple enough fix if they know about it. Screenshots can help.
Also, any reason you're on Dark Plus? Dark is actually better-performing/more compatible in most cases, and about the only thing you lose is the mouseovers on MDI window buttons.