Thanks so much for reporting this issue. Bricks 1.3.7 (stable release) will include some builder CSS fixes in regards to your report.
But it is impossible to cover all possible custom CSS cases. The best solution here is not to load those files in the builder panel in the first place. Bricks has a PHP function called bricks_is_builder_main() that returns true if the builder panel is being loaded.
I’ve added a code example about how to use it the to “Child Theme” Academy article as well:
You can also download the updated child theme code from your Bricks account.
I am going to close this post, as according to my tests those issues will be resolved in 1.3.7 (stable). If you are still experiencing any of them at that point, please let me know here.