I am pretty sure everyone tweaks css inside their respective theme, as we all need some sort of change that is not available. I would love to see the Custom CSS area arranged differently.

Now there is Global, Desktop, Tablet, Mobile landscape, Mobile and Admin with very small 300px editor.

I believe it would be best if the CSS categories were set into tabs and the CSS Textarea was 600 or 900 long making it more visually appealing to work with.