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Table of topic groups > Front page of CSS-guide > Extra pages > E What kind of non-standard (proprietary) CSS browsers support (introsection)

E What kind of non-standard (proprietary) CSS browsers support


What kind of non-standard (proprietary) CSS browsers support must look from different points of views:

  1. Proprietary CSS can be designed only for the internal usage of the browser, when CSS-files defines any kinds of default settings (preferences) of the browser. These kinds of style sheets are UA style sheets (UA CSS, UA = User Agent = any application, which use style sheets to define its preferences).
  2. It can be designed especially for define the interface of the browser, when it is UI CSS (UI = User Interface). This kind of CSS can be UA CSS, or document CSS (I handle these points of views shortly in the page 5[S]). I doesn't normally affect to presentation of the actual page, but it concerns rather just the interface, like the color of the scroll bars, mouse cursor etc.
  3. It can concern the presentation of the document itself.
  4. It can be designed for the Web-author. This kind of CSS can concern both the document and the interface.
  5. It can harmless to browsers, which don't support it. It can be also serious harmful for browsers, which can't interpret it.

The usage of What kind of non-standard (proprietary) CSS browsers support should be avoided in common Web pages. It can be a little bit used, but using proprietary CSS in my mind should be used following "moral principles":

Between standard and What kind of non-standard (proprietary) CSS browsers support are implementations of working draft level proposals for CSS3. W3C recommends to use non-finished specification only in special test pages. The usage of them should be limit only to intranet solutions. MS IE supports them most. Also Netscape 6.x supports a little unfinished CSS3 proposals. I don't handle them in this page just at all. I made however a list of proprietary and proposed CSS-features, which I have found (or I have read) to be supported in MS IE 5.5, Netscape 6.1 and Opera 5.12.

Note 1. The disadvantage of proprietary CSS is that the official CSS validator of W3C tells that the CSS is invalid. In order to avoid this problem, it is reasonable to define proprietary CSS in own CSS-files. With some script can be done a function, which finds the special CSS-file only for the use of certain browser. Indeed this doesn't help users of Opera, because they can choose, how they identify their browsers. A CSS-file, which have proprietary CSS, might always cause problems for some users of Opera.

Note 2. If special feature of MS IE are used, it could be find, if also such features, which work only in new Netscape/Mozilla and Opera are also used. They support much such standard CSS2 features, which are not supported in MS IE but which make browsing with previous mentioned browsers especially comfortable. Properly designed these features don't cause any harm to browsers, which don't support them. I have use one proprietary feature of MS IE but much more such features, which works only in Opera and new Netscape/Mozilla browsers. I have not in any connection tried in purpose to make harm to visitors, which use MS IE (I have however in purpose made this site so, that it doesn't work optimal in the Netscape 4.x series).