style the user topbar to be a bit more obvious (and not look like part of the browser)

[garrett]

One issue we previously had when deploying sites was the fact that the topbar looked a little too much like typical browser chrome.

This caused people to not notice the edit/create button at the top or any of the menus.

We should fix this by default.

I'm thinking that we might want to have something like this reside in theme.css, as it's a stylistic change that people will want to alter on their own website.

[garrett]

Here's a screenshot to show how we "fixed" this for the signed-in state on oVirt.org.

This affects all users who have editing rights on the wiki, including anonymous if $wgGroupPermissions['*']['edit'] and/or $wgStrappingSkinAnonNavbar is set to true.