I am intrigued about the tab design.
At the present time I have no desire to try and duplicate this design. I can see that this presentation works well for the way that Wikipedia have configured their collaboration model. Each page has a tab that allows the user to read, talk, view the source or view the history of the page. All this is pretty transparent to the general user as the tabs are reasonably innocuous and would only really be seen by those who wish to make edits.
The w3.css tab design
The W3 examples look different to the Wikipedia tabs.
The Wikipedia tabs have thin blue borders on the left, top and right of the selected tab. The non-selected tab has a light blue background with the same thin blue border on all sides.
The tabs and all hyperlinks have tooltips, the only thing that I would change is the underlines in the unselected tabs when you hover the cursor over them.