Probably related to bug 14586. Webkit doesn't populate document.styleSheets with stylesheets other than the default/preferred one (no way to access alternate stylesheets for example), so there is no way to use a Javascript stylesheet switcher. The following methods don't work: - inserting a new stylesheet through Javascript then enabling it - disabling the preferred stylesheet - enabling an alternate stylesheet - disabling (as in, object.disabled=true) the (X)HTML element that loads the preferred stylesheet (STYLE or LINK tags) Untested: deleting the DOM node instead of merely disabling it Test case: http://www.arcrachatcredits.org This website disables the stylesheet 'style-vert-css2.css' loaded through a STYLE tag in the head if the document's body is smaller than 640x400 (and re-enables it if resized above said resolution). The test case works on Firefox 2.0 to 3.7a5pre, IE 7 (real and emulated) to 9, Opera 10.10. It doesn't work in Konqueror 4.2, Chromium 5.0.339, Chrome 4.1.249.1045, Safari 4.0.5 (531.22.7).
I can't tell a difference between Safari, Chrome, or Firefox on this site. Please REOPEN this bug with a simple test case if you believe there is still an issue here.
I would expect that we still have issues in this area (and other browsers might too). But someone would need to create minimized test cases.