Implement relevant parts of genesis-hm's custom.css

[bobbingwide]

In the genesis-hm theme I used custom.css to style certain content.
While the content is still being displayed using shortcodes some of this CSS remains relevant.
There are 516 lines in the current custom.css files

Requirements

• Reduce CSS as much as possible
• Rework shortcodes to use blocks

Proposed solution

• Initially implement custom.css as is.
• Determine the need for the CSS over time.
• Either retain only the CSS that's necessary to maintain the original styling
• or improve the styling to no longer require the CSS.

[bobbingwide]

Determine the need for the CSS over time.

I've started doing this. Writing a blog post to check the results. https://s.b/hm/what-do-i-need-in-custom-css/
I started with unused CSS of 96.5%. It's now down to just over 50%. A fair proportion of that is CSS comments.
Note: Some CSS is still marked with a red bar even when it's actually been used. To test coverage you need to hover and probably give the field focus as well.

Improving custom.css is probably not as important as eliminating the need for font icons from dashicons / genericons.