I have deployed websites with Semantic-UI to Heroku 3 times. The first two times, it only took a couple of minutes to figure out what I was doing. The third time, it took hours and then eventual intervention from a classmate, because while this problem is incredibly simple to resolve, it isn't very well documented.

Okay, so you're using the Semantic-UI gem and you've deployed your website to Heroku. Heroku seems to think that everything is fine, but you go to your website and none of your Semantic-Ui styling is up! OH NOES! :( What do you do?

  1. Go into config/environments/production.rb and find config.assets.compile and set it to true (the default is false). What this does is essentially precompile the assets again if the precompile fails the first time.
  2. Run RAILS_ENV=production bundle exec rake assets:precompile and compile those assets!
  3. git add, git commit, and git push heroku master. Hopefully, that should make everything work.
Some of my classmates have reported that they have needed to download and add the Semantic-UI files in order to get it to run on Heroku instead of just using the gem. I personally haven't found that necessary, but if you are still having trouble, give that a shot. Hopefully, this helps others with this problem. It was a really easy fix, but for some reason this last round I found it very difficult to find resources on.