I think I finally figured out how to properly center images that are wider than the column (450 pixels). I couldn't seem to get all four cases (image<=450 pixels, image>450 pixels)x(IE, FireFox) working correctly. I finally resorted to using a different image class for wide images, which looks like this:
img.centerwide {
display: inline;
margin-left: -287px;
margin-right: -287px;
position: relative;
align: center;
text-align: center;
}
Of course, I'm sure this breaks every web design rule in the book and probably doesn't work for some of the less popular browsers. Oh well, it'll do for now until somebody complains. I really ought to learn about HTML and CSS properly.