The call to RenderToImage has an optional parameter of type CssData. Turn your stylesheet into a CssData object by calling the static CssData.Parse method and passing it the stylesheet (as a string). I have a couple of suggestions. I would remove all the inline styles and put all of the style information into the CssData object. That would make it much easier to debug. You might also want to start off with a simple stylesheet just to make sure you have everything set up properly.
Also, and this is probably unrelated to your real issue, but if you use the type attribute on a link element for a stylesheet, I'm pretty sure the values should be "text/css".
Also, and this is probably unrelated to your real issue, but if you use the type attribute on a link element for a stylesheet, I'm pretty sure the values should be "text/css".