Showing a hidden section causes child fields to expand (CRM 2015 On-Premise Update .1)

On an Incident form I have a 1 column tab, containing a 3 column section.  I have set it as hidden by default, and it gets shown via Business Rules by setting each field as visible on a condition. (I have tried it with JavaScript instead and had identical behavior).

When it does get shown, the section's fields behave weirdly  as pictured.  Rolling over one causes the other to move, and clicking one causes them to move even farther. 

Is there anything I can do?  When I have the section set as visible by default it does not do this.  It's only happened, so far, when showing a section via Business Rules or Javascript.