So i just wrapped up some initial styling for a personal website i'm working on, http://www.sociospatial.com/

Looks fine in firefox. Has some minor issues in chrome/webkit, which I'll iron out later. Haven't dared to load it up in IE yet. In Opera, though, I'm having a problem that I don't know where to start.

So without having to paste alot of code, I have a wrapper div and a footer div, just so that I can have the footer hug either the bottom of the viewport or the bottom of the page, whichever is lower. I also wanted some background elements to the page, but I wanted them to hug the bottom as well (load up the page in firefox and resize to viewport to see), so I ended up with something like this:

Code:
<div id="footer">
  <span id="left-bg"></span>
  <span id="right-bg"></span>
</div>
and the styling for these is something like (I can post the actual/more if need be)
Code:
div#footer {
  position: relative;
  height: 25px;
  width: 100%;
}

span#left-bg {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 400px;
  height: 600px;
  background: transparent url(some-url.png) no-repeat 0 0;
  z-index: -1;
}

span#left-bg {
  position: absolute;
  right: 0;
  bottom: 0;
  width: 400px;
  height: 600px;
  background: transparent url(some-url.png) no-repeat -400px 0;
  z-index: -1;
}
in firefox/webkit at least, these function as i want, so I have 2 spans that spill up through the top of the containing footer div, but still hides behind normal content. If my wrapper content is minimal, it appropriately hugs the bottom of the viewport and i don't have any vertical scrollbar. If I have a lot of content in the wrapper, I have a vertical scrollbar, but the footer and the spillout background elements are all waiting for me at the bottom of the page.

in opera (9), the two spans hug the bottom of the (initial) viewport as I would hope, but I *do* have a vertical scrollbar (even when the content in the wrapper does not necessitate it), and scrolling down reveals that I have a *huge* amount of space that's just empty body background below the footer. This empty space seems vaguely correlated with the "height" values of the spans (the lower the height value, the smaller the empty black background space under the footer), and the vertical scrollbar goes away completely under one of these conditions:
a) i add "overflow:hidden" to the div#footer styling (but of course this stops the span elements from spilling through the top)
b) using the W3-dev opera tools, if I disable both spans
c) after I disable both spans, I enable only one or the other (if I just disable one after both have been enabled, the vertical scrollbar stays, so I have to disable both first).

i'm not quite sure what exactly is going on here, nor really what issue I'm trying to track down (I don't know what to enter for a google search, for example) - I'm kind of new at this. Anyone have any clues to contribute? I'll add more information if needed.