Disable Top fixed wrapper at lower resolutions

agreed, but I dislike having a lot of css overrides/repetitive classes.
What I WOULD like though is the ability to add extra CSS files.

for example, on the custom CSS tab, have the option to 'Add CSS File' with the ability to name it and then add your custom css.

you can add your own file using the custom code area, so you can disable bootstrap and load you own this way

If I do it this way, I assume the added CSS file will not get removed when I make changes to the template?

if you place a file directly in the template folder, it shall not be removed