I've set up a simple sidebar on an otherwise fairly default wiki.  The sidebar uses css float:right and sits above most pages quite nicely.

For example, my wiki's [front](http://www.cse.unsw.edu.au/~cs3431/wiki/) and [news](http://www.cse.unsw.edu.au/~cs3431/wiki/news/) pages show the sidebar nicely floating on top of the background.  (As a side note, I had to add:

    #sidebar {
    	border: 1px solid;
    	background: white;
    }	

to <code>local.css</code> to get the border and make sure that the RSS feed's grey title didn't show through on the news page.)

Unfortunately, the [recentchanges](http://www.cse.unsw.edu.au/~cs3431/wiki/recentchanges/) page doesn't look so nice - the sidebar appears below the recentchanges list.

I don't understand why the sidebar is appearing below the recentchanges inline, but above the news inline.