Preview iframe has no background, causing the admin page background to show.

[Dykam]

The default color of pages are white, so you never give a page a white background as markup. html and body have no background, no problem, since the browsers renders that white. But the preview iframe is translucent as well, showing the gray background of the admin page. The fix is to set background-color to white on the iframe.

Besides that it works fluently.