This doesn't do what you think it does. This will create a selector that will look like:

    .department-for-business-innovation-skills,
    .uk-atomic-energy-authority .contact { border-top: #bada55; }

Which means the bis pages won't get the colour any more. 

I also don't like this approach of adding a class for every org. It doesn't scale very well when there are up to 300 different orgs that will want colours (as this block is currently outputted for every selector that has an org specific colour). There is a story to deal with exactly this: https://www.pivotaltracker.com/story/show/38409467