I am trying to make a WebBrowser control on my Windows 7 Phone app transparent, so it can have the same theme as the rest of the app, but I have had no success with anything
As an alternative to (or maybe in addition to) trying to load some initial content to set the webbrowser control to be showing a color to match the page background you could just set the opacity of the control to be 0 and then change it to 1 when the Navigated event on the control is fired for the first time.