When resizing (using CTRL+) in Firefox, the sidebar calendar "slides over" the edge into the content area. This occurs in all themes with which I've tried it so far, and no matter how many columns there are or in which column the calendar is placed (aside from in the main content column - where it works fine, but that's never where I want it!) There seems to be no way to prevent this occurring, I've tried about a hundred different combos of margin, padding, sidebar width, calendar width, you name it.
This is the simple calendar that's standard with wp, btw - nothing fancy but contrary to some posts I ran across while searching, I like it.... I use it all the time, but it's awkward that it won't "live" in the space assigned to it!
Anyone have any ideas about forcing this problem child to stay in its corner?