well yes and no. Seems to be some interference with <div class="sidebar-no-widgets"> just above the first spoiler. Something about that class is kicking off something that interferes with tables with width=100%.
Just put this as the first text in your article to demonstrate:
<table style="width:100%" >
</table>
Something takes the first table of 100% and stretches it out. Since es uses tables, the first one is modified by the same mechanism.
-d