Consider deprecating `o-form_group`
It seems to serve no purpose other than adding 30px of bottom margin to whatever it wraps. It seems like it could be replaced by putting that bottom margin on fieldsets and using the u-mb30 utility class when a fieldset is not available.
See discussion here: https://github.com/cfpb/capital-framework/pull/539#issuecomment-315196995
It's not always wrapping a lone fieldset, in the Sandbox example, the two individual text inputs also live in a group. Well have to spend some time thinking this through for all forms we're currently using.

https://cfpb.github.io/capital-framework-sandbox/components/cf-forms/
Spoke in person, I'm convinced to remove the groups and rely instead on fieldsets.