I'm fine with @drewwills 's recommendation to retain the activity-portlet-specific CSS styles in an element in the activity-portlet-specific JSP.  If I were doing it I'd favor putting framework styles in the framework SASS and LESS because it's a framework portlet. 

I'd look for opportunities to make those styles framework-general rather than activity-portlet-specific once there's another opportunity to use them in the framework or in a framework portlet.  On glance, looks like these styles are about graphs/reports.  Great.  Someday there will be another framework portlet that produces graphs/reports and wants to style reports boxen.  Should probably use the same report styling as activity portlet.  But I'm more than fine with deferring that refactor to generality to that fateful moment when duplication actually occurs.

In the meantime: I'm fine with this changeset once it 1) works and 2) doesn't introduce a commented out CSS link, since that's just confusing.  If it goes back to style element in the activity-portlet-specific JSP, ok.  If it goes to declaring the CSS styles for this framework portlet in the framework SASS/LESS, also ok.  If it checks minified CSS files into source control, eh, I'm not thrilled, but I'm not going to stand in the way.  Better mobile view sounds like a good thing.

Pro tip: this pull request would be even stronger with screenshots of what the portlet looks like resultingly. :)