Remove CSS only used for HMRC manuals
Remove CSS only used for HMRC manuals

I'm trying to restructure this CSS a bit to be less complicated, as part of that I'm removing HMRC-only styles which will be sorted out when the next iteration of HMRC manuals is complete

alphagov/manuals-frontend,alphagov/manuals-frontend,alphagov/manuals-frontend,alphagov/manuals-frontend