When you place two images side by side in html, its good idea to make sure that both images are on the same line in code.
i.e.
<img> <img>
as opposed to
<img>
<img>
The reason for this is that some browsers (IE and Firefox anyway) put a text node(with a space in it) in between if the images are seperated with a carrage return. This is can annoying if you want the two images to join and you want no padding in between what-so-eva.