Fix responsive styling of delta text on KPI modules.
Fix responsive styling of delta text on KPI modules.

Story: https://www.pivotaltracker.com/s/projects/911874/stories/70925872

tijmenb/spotlight,keithiopia/spotlight,tijmenb/spotlight,alphagov/spotlight,keithiopia/spotlight,keithiopia/spotlight,alphagov/spotlight,tijmenb/spotlight,alphagov/spotlight