I've noticed a little problem when viewing my site:  Different pages or posts appear to have different widths.  This is kind of impossible because I wrote my template by hand, and I made all the pages and posts look pretty much the same.  So I searched to see if anybody else had the problem.  The answer is yes.  The problem is that Firefox doesn't have a vertical scroll bar unless there's content that extends past the bottom of the browser window.  This sounds good, except that it causes the problem that I just mentioned.  This site says to use html {overflow-y: scroll;} in the style sheet.  It also recommends a couple other similar solutions, none of which I tried because the first one worked.  This problem doesn't occur in Internet Explorer or Opera because the vertical scroll bar is always displayed, though it's grayed-out when not needed.  This solution displays a grayed-out scroll bar, whether there's content past the bottom of the window or not.