Repair/Rebuild Resets CSS?

I just ran a repair/rebuild and it reset some of my CSS. Is this normal?

Hi,

This depends where you made your customizations.
Any customizations should be made in the custom/ folder for safe upgrading.

If you made them in the custom module, does clearing your cache/ CTRL + F5 have the CSS changes re-appear?

If not, What changes did you make specifically?