That is actually exactly what I want (why didn't I think of it...)! Thank you. In fact, wkhtmltoimage supports svg and does a great job of rendering, say, GitH

That is actually exactly what I want (why didn't I think of it...)! Thank you. In fact, wkhtmltoimage supports svg and does a great job of rendering, say, GitHub or techmeme. It falls over on formatting mathoverflow.net, but I think the same technique could be changed a bit to more closely resemble what actually gets layed out on the page in a running browser instance.