This problem was present in 3.0.5 as well as in 3.1.0-rc1. URL: http://www.lemis.com/ CSS: enabled or disabled Summary: Won't render HTML with comments before <!DOCTYPE>. Pages on this website aren't rendered, just displayed as source code. Although they are XHTML, this doesn't appear to be due to this bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1036382 If I save the file as lemis.xhtml and remove the two comment lines before the <!DOCTYPE> declaration, then it renders when I load it with file:// or http://, otherwise it doesn't. My reading is that comments there are valid for HTML 4 (which is declared in the page's <!DOCTYPE>) since the standard says: White space (spaces, newlines, tabs, and comments) may appear before or after each section. https://www.w3.org/TR/html401/struct/global.html#h-7.1