Admin Color Schemes: Block Editor Support

[marekhrabe]

The general support for admin color schemes is being added in #17828. This specific PR extends it so the color schemes also apply to the block editor, just as core color schemes.

Changes proposed in this Pull Request:

• uses Sass variables to generate CSS vars the block editor uses to adjust its colors

Jetpack product discussion

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Does this pull request change what data or activity we track or use?

No

Testing instructions:

• Follow instructions from Admin Color Schemes: generate wp-admin color schemes from Calypso counterparts #17828 and activate yourself some of the new color schemes
• Open the block editor and check if your color scheme has a desired effect on the editor UI. The editor doesn't change a lot but you can see those colors for example in the toolbar buttons (block inserter and publish) or form elements in the sidebar.

A few examples of the green color propagating from the Sakura scheme:

Compared to the Sunset scheme:

Proposed changelog entry for your changes:

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Fixes #18016

[jetpackbot]

Scheduled Jetpack release: January 12, 2021.
Scheduled code freeze: January 4, 2021

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Generated by 🚫 dangerJS against 8ce7f60

[frontdevde]

LGTM! 👍

I rebased with feature branch and changed to use the highlight color so it matches with the button color of the color scheme.

e.g. with Classic Bright the button color of the scheme is pink

Using $base-color the buttons were blue, now with $highlight-color they are pink too.

Before	After

[anomiex]

Code seems straightforward enough. I see @frontdevde already tested.

The base branch was changed.

[frontdevde]

Approving again after rebase 👍

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello marekhrabe! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer and confirm D54279-code works as expected before merging this PR. Once this PR is merged, please commit the changes to WP.com. Thank you!
This revision will be updated with each commit to this PR

[marekhrabe]

after some fight with the build process on wpcom, r218390-wpcom