max-width: calc(100% - 22px) !important;
Well, xenforo has a nice feature, where you can click an image to enlarge it. However this one line of CSS makes it impossible. Removing the line makes it work again. I'm curious if there is anyway to keep the click to enlarge after applying the max-width css.
edit: It turns out I had a left over '!important' on the max-width causing a conflict with the feature. With the removal of the !important the click to enlarge worked again.