I updated to Thesis 2.1 and my multisite CSS is not working.

In Thesis 2.1, we changed the way Multisite installs handle CSS, so there’s an extra step you’ll need to take if you’re using Multisite; please see this Troubleshooting article for more information.

If implementing the information from that article does not work for you (or if you are using nginx), please submit a support request, and our staff will escalate your issue to the development team.