It would be great to be able to manually edit our CSS classes in a text file and add some other rules which webflow visual editor currently doesn't support

Actually I was trying to add display-font: swap; rule to the @font-face in order improve the website performance also to score high on google audits but webflow doesn't allow us to do it.

If we want to improve the performance we should be able to edit our css file manually. Yes it is possible to put your custom css code but that doesn't really gives us full freedom.

The other problem was, I wanted to let browser choose which image format to display unless it doesn't support .webp so there I need to be able to edit the CSS and HTML manually.

These were just 2 basic problems, with that option we can basically do anything we want.