Mobile browsers that only read the handheld style sheet will never see the potentially harmful CSS properties defined in screen.css. Mobile browsers that read screen style sheets, and handheld or media queries style sheets will not be affected by the harmful properties in screen.css, since they're canceled by antiscreen.css. Finally, PC browsers will happily ignore both antiscreen.css and handheld.css.

One practical problem remains: if your screen.css style sheet is long and regularly modified, the creation and maintenance of antiscreen.css can be quite a challenge. Who wants to find out which CSS rules include one of the noted properties among the thousands of properties potentially set in a rich style sheet? And who wants to maintain such a list manually?

Fortunately, computers do. If your browser supports the DOM Level 2 Style specification, you can use a script run from your browser on a given page (and more easily so through this bookmarklet) to identify which style sheets in the page you want to cancel.