Feature Request - Custom CSS Classes

I've been working on a project lately where to get the exact design I want, I needed to add a decent amount of my own CSS. I filled up the 3000 character limit in the theme CSS by the time I had gotten 1/4 the way through my project and then had to shift the design. My feature request below would reduce the issue I faced.

In my particular case, I needed to add my own CSS styling to many 'groups' to get exactly what I wanted. When inspecting and grabbing the CSS class, each group had it's own unique CSS class (which was actually good as I was able to target exactly what I needed), which meant I had to add all of those unique classes to the theme CSS. Additionally, I had to adjust some of the parent divs to the groups to adjust the CSS flexbox settings to get exactly what I wanted. The unique class names where quite long which filled up the 3000 character limit in the CSS quite quickly.

It would be of great help if we would be able to add our own CSS classes to any element, group, section, etc. so that we can then go to the theme css and apply styling to our CSS class and reuse that CSS class in multiple places. If you are familiar with Wordpress's Gutenberg, that is an example where you can add either your own CSS class or ID to any element, row, column, etc. on the page. This would make it far easier to apply your own styling, reuse the CSS classes you make and eliminate the need to inspect a page, grab the CSS class that exists already and then add your styling. It would also reduce the number of characters needed to be added in the theme CSS, which would help against the 3000 character limit.