I do not see these overlapping in FF or IE??
But if you will have no more than 3 you can space them out by changing the value to 30% in
Code:
.attribImg {
width: 30%;
margin: 0.3em 0em;
}
For some reason where others have issues with additional images you are getting them when you do not want them - as this is a naming auto magic thing you can either change to unique names where this seems to be being picked up as a bas image name and then the additonal (base name highlighted for clarity)
SquarePanelSingleShort.jpg
SquarePanelSingleShortNarro.jpg
Or if you never want to use additional images:
admin > config > images > Product Info - Number of Additional Images per Row > set to "0"