A small adjustment to the page background color per yesterday's conversation with nacin, from #eee to #f3f3f3. This retains enough contrast with white widget containers while making for a more comfortable reading experiences on pages that heavily use the default background color, like the About page. A few adjustments to go along with it:

- Horizontal rules on the About page are lighter, to match their previous level of contrast with #eee
- Eliminated the .flush-top class on <hr>s on the About page since we want the styles applied to all About page <hr>s.
- Color schemes should match the bottom border of active tabs to the scheme's body-background variable.
- Lighten the comment background color on the Dashboard activity widget to keep adequate contrast with the new lighter body background.

See #25858.


Built from https://develop.svn.wordpress.org/trunk@26788


git-svn-id: http://core.svn.wordpress.org/trunk@26675 1a063a9b-81f0-0310-95a4-ce76da25c4cd