Unicode and HTML with detectable errors. Currently, Gecko browsers such as Firefox, abide to this rule, whereas the bulk of the other common browsers that support HTML as XML, such as Webkit browsers (Chrome/Safari) do allow the encoding of XHTML documents to be manually overridden. Many browsers are only capable of displaying a small subset of the full Unicode repertoire. Here is how your browser displays various Unicode code points: Some web browsers, such as Mozilla Firefox, Opera, Safari and Internet Explorer (from version 7 on), are able to display multilingual web pages by intelligently choosing a font to display each individual character
Quirks mode Web Consortium, which maintains the XHTML specification, suggests that authors of XHTML documents could consider omitting the XML declaration. Henri Sivonen compiled a list of various document types and how they are treated in the most common browsers, showing whether pages are rendered in Quirks, Standards, or Almost standards mode. The criterion used for "Almost standards mode" is non-standard table cell height rendering. This table applies to content served with the Content-Type text/html. Content served with the Content-Type application/xhtml+xml is rendered in Standards mode in Chrome, Firefox, Internet Explorer 9, Safari, and Opera. Internet Explorer 6, 7, and 8 do