Some text is invisible in the How to Format help block because of a bad combination of text and background color: That's meant to read ► backtick escapes `like _so_` but the backquoted ...
In the 'Questions' page point your mouse at the 'line' which separate the tabs(Newest, Frequent, Votes, etc) and the questions and see the mouse pointer transforms in between the two shapes (Hand ...
This appear to be specific to Stack Apps. The text is centered on every other site I've tried. See below: Compared to how it should appear:
The API Help page's CSS file, located at http://sstatic.net/so/all.css, is current returning 404 for me: <div id="header"><h1>Server Error</h1></div> <div id="content"> ...