Revert 28517 for now. Puts non-standards-compliant code in shared.css to work around a Firefox/IE bug, and consequently breaks display for Opera, Safari, Konqueror, and any other browser that behaves correctly here (probably also future versions of FF and IE). It fixes that in Monobook only, and only for a small subset of affected browsers (Opera 7 and KHTML). The correct code should be in shared.css, with workarounds for IE and Firefox for all skins.
Furthermore, it's not clear to me why 1.2em was chosen, and it doesn't always seem to work. See <http://encyclopedia.tw/wiki/%E8%AC%9B%E5%80%92%E7%B7%9A> for a page (non-Wikimedia, non-English) where the edit links are noticeably too high due, apparently, to this.
See also bug 12340, caused by this.