1.9.5: Dashboard columns take up full width

In my 1.9.5 installation I noticed that I can only place dashboard widgets above or below each other instead of side-by-side in 3 columns.  It looks like the margin of each of the three columns is taking up the entire width of the parent container.  The blue part shows the width of one of the '.elgg-col-1of3' containers, while the orange color shows the margin:

It's possible that some CSS or JS from another plugin I'm using is interfering with the dashboard, though I haven't found anything yet.  Before I continue to investigate that, are there any known issues with dashboard widgets in 1.9.5?  Has anyone seen an issue like this before?