How to ovewrite the default modal style on theme?

Your software
My Mautic version is: 3.3.3
My PHP version is: 7.4
My Database type and version is: 5.5.35

Your problem
How to ovewrite default modal style on theme?
I try use theme GitHub - Custonext/mautic-theme: A basic theme for Mautic, the open-source marketing automation suite. It includes styling of forms and pop-up items. Basic styling of emails and pages is included to be completed at a later stage., but this theme doesn’t ovewrite default style modal.

These errors are showing in the log:

Steps I have tried to fix the problem: