I think most of this css is in a module.

One of these two: https://github.com/mozilla/popcorn.webmaker.org/commit/6c9b2cdfd7e8f3426c80c26b39cd52d6888938ea#diff-0a08a7565aba4405282251491979bb6bR8

This also might help: https://github.com/mozilla/popcorn.webmaker.org/commit/6c9b2cdfd7e8f3426c80c26b39cd52d6888938ea#diff-9b4fa9497ba604e43bcfaedd381fd6bbR2 but I forget.