Sorry....I use an older version (Dreamweaver 4) so I wouldn't have a clue where to tell you where to look specifically for options or settings.

I did a search though and found this statement at another forum....don't know if it helps:

Quote....

"I use Dreamweaver MX 2004. The background color is defined in CSS. Because the login screen has a background color of white, when you preview the page or are in design mode in Dreamweaver MX, the background will appear white. This is because of nested design elements in the page. But once the page is parsed by PHP only the correct elements will be shown. "

Unquote....

About all I have on that question....