Fix for uneven column heights

I'm not sure. If it's the exact same offset height as the current element plus height normal rendering should have it on the same line. This only changes if you're using `margin-top: -1px` or something. But at that point maybe you should check if they overlap using `itemEls[i].offsetLeft < itemEls[0].offsetLeft + itemEls[0].offsetWidth`. That said, whichever you think is appropriate.