Override from template not working in Joomla 4

Override from template not working in Joomla 4

Hey folks,
First time now using DJ Image Slider with Joomla4 and finding that override from template is not working properly.
Copied file to template/css and even without any modifications full width slider has a 30px (or so) margin on the left with then horizontal scroll bar and images are stacked. Using the same file as is and selecting Default Theme, fixes all. 
The same issue presented when I created a new theme (again.. simply copied default and before making any changes.)

At this point, there is little value in customizing if changes will likely be overridden by future upates.

Help please!? :)
Thank you!