Wow, I found it surprisingly quickly.

I had changed

.centerBoxContents, .specialsListBoxContents, .categoryListBoxContents, .centerBoxContentsAlsoPurch; .attribImg {
float: left;
}

to

.centerBoxContents, .specialsListBoxContents, .categoryListBoxContents, .centerBoxContentsAlsoPurch; .attribImg {
text-align: center;
}

I removed .attribImg from that command, put it back as a float: left, and the images appear correctly in rows. Yay!