You have to be a little careful here, as certain versions of IE won't render MHTML assets the second time they area loaded, but again only under certain circums

You have to be a little careful here, as certain versions of IE won't render MHTML assets the second time they area loaded, but again only under certain circumstances. In Cappuccino, in addition to building in all the known workarounds (serving mhtml files with content type of text/plain, adding cache busting parameters if needed), we actually perform a runtime check of the supported feature before we use it. So, we try to load a single 1px dataURL image, and if that fails we try to load a known 1px MHTML image, and if that fails we fallback to the original image resources.