When you create a Website Template / Theme using Thunder it automatically generates a number of CSS files, some in the Global folder others in the Styles folder as well as a bunch of images in the Images folder:
Question: When are the CSS files in the Styles folder used?
Then, if you decide to use a resource package like Bootstrap there seems to be some overlap. For example the resource package for Bootstrap has a reference to Normalize which seems to be an overlap for what the Website Template/Theme's reset.css is intended for.
Question: If you're using both a Theme and a Resource Package should one first clean up the Theme's CSS files, i.e. remove them and then add new ones simply to customize the output from the Resource Package so as to preserve upgradability for Resource Package?
Question: If the answer to the above question is 'Yes' remove those CSS files, then what else needs to be considered in terms of a clean up so that there isn't additional unnecessary CSS being rendered?