I agree with a poster above who spoke about self policing at games. It’s only ever one or two idiots who shout racist comments (apart from that Bulgarian mob), but hundreds of disgusted fans surrounding them do nothing about it.
Why not get a steward over and point them out? There will be plenty of witnesses.
I’ve stood up against racists both at the football and in every day life on a few occasions.
You can’t stop someone from being racist by outlawing it, but you can control it in certain public domains if decent folk had a bit more about them.