Last modified: 2007-01-15 16:31:28 UTC
Every page contains a CSS class containing the page title, e.g. "page-Foobar" (see bug 5795). However, because the behavior is implemented in (at least) two places, the generated class names differ between skins. In Monobook, the behavior is correct, but in Standard, the class is escaped wrongly, using escapeId instead of escapeClass, so that the class name can contain dots (which is, while syntactically valid, unusable in CSS selectors). See r17120, esp. the non-change in Skin.php, where escapeId should have been changed to escapeClass.
Thanks for the report! Fixed in r19299.