Assembler: Unset white background (try 2)

[taipeicoder]

Fixes #89324

Proposed Changes

This PR fixes the issue where the background colors from global styles are not applied in the block renderer in the Assembler. This is caused by https://github.com/WordPress/gutenberg/pull/59377/files, where the background is explicitly set to white.

I don't feel great about this approach due to the performance penalties and that we are imposing CSS specificity, but since it's a short-term solution, I think it's okay we'll just remove it at a later date.

Note that the issue only affects Safari.

Testing Instructions

• Using Safari, head to the Assembler.
• Select some patterns, then styles.
• Ensure that the background color from the global styles is applied correctly to the pattern in the large preview.
• Ensure that Chrome and Safari also works as before.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• https://wpcalypso.wordpress.com/devdocs/docs/testing/index.md for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

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[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/block-renderer-white-background on your sandbox.

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~306 bytes added 📈 [gzipped])

name         parsed_size           gzip_size
patterns          +379 B  (+0.0%)     +160 B  (+0.0%)
import-flow       +379 B  (+0.0%)     +146 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[arthur791004]

Tested and looks good to me 👍

How about removing the style from the head element and re-adding them like the previous approach?

[taipeicoder]

Tested and looks good to me 👍

How about removing the style from the head element and re-adding them like the previous approach?

In the previous approach I had to use background-color: unset !important, but then it would be the same issue since the global styles CSS still doesn't enough specificity over the background-color: unset !important 🙁
Simply using background-color: unset without the !important part doesn't fix the specificity issue in Safari.

This also causes a regression issue where the pattern list preview would not have the background color applied.

Another approach we could do is to use JavaScript to remove the <style> injected by the Iframe component then re-add it, but I think the solution is not great either. WDTY?

[arthur791004]

Another approach we could do is to use JavaScript to remove the <style> injected by the Iframe component then re-add it, but I think the solution is not great either. WDTY?

This is what I mean 😆 I'm fine with both and I assume it could be resolved after upgrading the package soon!

[taipeicoder]

Let's merge this quick fix first, and we can time-box the other proposed solution 🙂