Setting Button block to Outline Style causes CSS output order to change and cause conflicts

[eric-michel]

Description

Typically, wp-block-library-inline-css is output before global-styles-inline-css so that styles from global-styles-inline-css (i.e. those from theme.json) override those from wp-block-library-inline-css (like the various WP default colors and font sizes).

For some reason, setting a Button block on a page to Outline style causes wp-block-library-inline-css to print after global-styles-inline-css, causing it to override any same-name settings in theme.json.

This is an absolute disaster for us, because our theme defines a normal font size, and now it is being overridden with by the WP default of 16px on any page that uses an Outline button.

Step-by-step reproduction instructions

• Spin up a fresh site on WP 6.6.1 running the Twenty Twenty Four
• Alter the Twenty Twenty Four theme.json file to include a font size with the slug normal that is something fairly large, like 2rem
• Make a page with some text using that font size and preview it - note that the text is correctly sized to 2rem
• Add a button with the Outline style on the same page and preview it again - note that the text is now 16px

Screenshots, screen recording, code snippet

Normal print order when an Outline style button is not on the page:

Print order with an Outline style button on the page:

Environment info

WordPress version 6.6.1
Twenty Twenty Four theme (only modified to add a font size to theme.json)
no plugins

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

[talldan]

@eric-michel Thanks for reporting this and providing such a detailed bug report. I've put a fix together in #63918.

I'll also work on a core patch and aim to get this released in 6.6.2

[eric-michel]

Thank you so much @talldan! Once the problem was figured out my next step was going to be to figure out who I had to beg to get this added to a point release, so you saved me a lot of anxiety there.