I use Chrome and http://www.aaai.org/Conferences/AAAI/aaai13.php for test.
There is a structure like that.
<div class="content">
<div class="right">...</div>
<div class="left">...</div>
</div>
I just have no idea about why the "content" div's size is 940px * 70px which is much smaller than the size of the "right" div and the "left" div.
Sorry for not knowing how to screenshot for this problem