This is style for the "MySkin" skin on Wikipedia, Wiktionary, and Wikinews (note: the default is Monobook; set to MySkin in your account preferences). It's reminiscent of Cologne Blue, but has a single, flexible column with the header doing more work.
It's mostly for my own benefit, so it has only been tested on the English versions and may be missing something that I haven't encountered on a page since I started paying attention to things like info boxes and notices. I also browse Wikipedia with script off, so I didn't bother styling script-generated content. Updates will be forthcoming as it gets more organized.
Notable effects: personal bar links ("my talk", "my contributions") appear on hover of the user name in the upper right, unobtrusive search box below that, lock icon appears translucent on the upper right like the default style, not-yet-created links are clearly denoted with italics and a superscript question mark at its end (at least with full-text new edit links turned on).
Update (3/2): stopped hiding some of the usually-useless thumbnail-type-classed boxes; they actually have content in them sometimes, it turns out
Update (2/4): added style for some standard Wikinews elements and added en.wikinews.org moz-document rules. If you don't want the region links visible on Wikinews, just hide #p-regions and comment out #column-one's modified height under "/* wikinews */" near the end.
Update (1/11): "new" page links correctly styled when the anchor's inside an element with the class (e.g., in #p-actions where it has li.new).
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/* Your ad can be here instead. 10K unique visitors for $5/day. Mail me. */
}