Libre 2 - Post title and blocks are left-aligned in the page/post editor

[rw-ye]

Quick summary

A customer in chat reported issues with the post title and blocks such as the Image block being left-aligned in the post editor instead of being centered. I was able to reproduce the issue on my own Simple and AT sites with the Libre 2 theme active. No issues are shown on the front end, however.

Screenshot of Post Editor

Steps to reproduce

1. Create a new page/post
2. Edit the page/post
3. When adding a title or a block such as the Image block, it will appear left-aligned in the editor instead of centered.

What you expected to happen

For the post title and content to be centered in the editor

What actually happened

The post editor shows the title and blocks left aligned

Browser

No response

Context

Customer report

Platform (Simple, Atomic, or both?)

Simple, Atomic

Other notes

No response

Reproducibility

Consistent

Severity

Some (< 50%)

Available workarounds?

Yes, easy to implement

Workaround details

The workaround is to disable Use theme styles in the post/page editor Preferences > Appearance tab.

[rw-ye]

Closing because of duplicate issue -- https://github.com/Automattic/themes/issues/7749