Remove editor styles from front-facing stylesheets

[aristath]

In order to avoid some duplicate rules between front-facing styles and editor styles, some rules were placed in front-facing stylesheets.
That saves some time for developers, but at the same time is not optimal for visitors, and that has to be more important...
With WP powering 35%+ of the web, even the smallest amount of data we save saves an enormous amount of energy. Shaving off unused front-facing styles, no matter how small that amount is, adds up to huge energy savings and promotes a more sustainable web. It's data that is saved on each page load, on a gigantic scale so every byte has to count.

This PR moves editor styles to editor.scss files. In the case of colors, in order to avoid duplicating a huge chunk of code, these were moved to mixins which then get included where needed.

[jasmussen]

What a wonderful PR. Thank you.

High level: I agree with the assessment, code looks good, and this all tests well for me. I'm definitely 👍 👍 on this one.

It's also a biggish change. What's the best way of testing that this doesn't regress any color related aspects of themes? Outside of testing a variety of themes and testing foreground and background colors as well as gradients?

[aristath]

It's also a biggish change. What's the best way of testing that this doesn't regress any color related aspects of themes? Outside of testing a variety of themes and testing foreground and background colors as well as gradients?

I tested it with the twentytwenty and another random theme, didn't see any issues (had to disable custom palettes from the theme and enable gradients)

The PR may look a bit biggish, but in essence it just moved around some CSS to be where it's supposed to be. The styles applied are exactly the same as they were.

On a side-by-side comparison I didn't see any differences in the frontend or editor, both for solid colors and gradients 😄

[jasmussen]

I share your assessment that it shouldn't be a massive change. I'm only cautious because I know that there are often ripple effects from the preset colors and gradients. So I hope that Kjell (CC'ed as reviewer) has time to take a quick look, and hopefully we can get this in soon. Thanks again.

[kjellr]

I share your assessment that it shouldn't be a massive change. I'm only cautious because I know that there are often ripple effects from the preset colors and gradients. So I hope that Kjell (CC'ed as reviewer) has time to take a quick look, and hopefully we can get this in soon. Thanks again.

This looks great to me, thanks @aristath!

[jasmussen]

🔥🔥🔥