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.