Yes, most of them do, in fact they are told so since CSS2.1 standard. But most of implementations did not allow rules scoped to @document, so was not very conv

Yes, most of them do, in fact they are told so since CSS2.1 standard. But most of implementations did not allow rules scoped to @document, so was not very convenient to use. Oh, just Chrome blatantly ditched it recently [0.1]. From comment in this very thread it seems is is still used in Safari [0] nowadays. [0] https://news.ycombinator.com/item?id=17355354 https://news.ycombinator.com/item?id=17355354 [0.1] https://code.google.com/p/chromium/issues/detail?id=347016 https://code.google.com/p/chromium/issues/detail?id=347016 --- Recycling my very first comment here at HN from 2013 [5]: In Firefox it is userContent.css and userChrome.css [1] (loaded at startup), in Google Chrome custom.css [2](this file is 'live'). IE [3] and Opera [4] have something like this as well. [1] http://www-archive.mozilla.org/unix/customizing.html http://www-archive.mozilla.org/unix/customizing.html [2] http://code.google.com/p/chromium/issues/detail?id=2393 http://code.google.com/p/chromium/issues/detail?id=2393 [3] http://windows.microsoft.com/en-US/windows7/Use-your-own-sty.. http://windows.microsoft.com/en-US/windows7/Use-your-own-sty.... [4] http://www.opera.com/docs/usercss/#user-mode http://www.opera.com/docs/usercss/#user-mode [5] https://news.ycombinator.com/item?id=5436309 https://news.ycombinator.com/item?id=5436309