[KarunyaChavan]

Trac ticket: https://core.trac.wordpress.org/ticket/65433

When a user inserts an empty heading block in the editor and applies an "Underline" or "Strikethrough" text decoration, the browser attempts to underline the pseudo-element's whitespace character. This interaction causes a stray, visible hyphen-like artifact to render inside the editor above the empty block as

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What this Changes

• This PR updates the post-section-dash mixin in sass/mixins/_mixins-master.scss to use an empty string (content: "";) instead of content: "\020".
• By removing the whitespace character, the pseudo-element no longer contains an actual text node.
• Since the element has explicit display: block, width, and height properties, the decorative dash continues to render identically on the frontend and backend.
• However, because there is no text content, the browser can no longer underline a whitespace character, completely resolving the visual bug in the editor without requiring any editor-specific CSS overrides.

Use of AI Tools

AI assistance: Yes
Tool(s): GitHub Copilot
Model(s): GPT-4o
Used for: To verify optimality and efficiency of the patch.

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[github-actions]

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[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs.

Core Committers: Use this line as a base for the props when committing in SVN:

Props karunyachavan84, sabernhardt, karmatosed.

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

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[karmatosed]

There are merge conflicts with this, if we can get a new patch worked on, happy to do that.

[sabernhardt]

I applied the patch cleanly via Tortoise SVN, but it would be good to refresh the PR again after r64610.

Test Report

Patch tested: https://github.com/WordPress/wordpress-develop/pull/12121.diff

Environment

• WordPress: 7.2-beta1-64606-src at revision 64673
• PHP: 8.4.0
• Server: Apache/2.4.62 (Win64) PHP/8.4.0 mod_fcgid/2.3.10-dev
• Database: mysqli (Server: 9.1.0 / Client: mysqlnd 8.4.0)
• Browsers:
  • Firefox 158.0, using private window for the front-end screenshots and default window to show the editor
  • Edge 155.0.4283.62, with Explain & Send Screenshots extension
  • Google Chrome 155.0.8059.80, combining 3 screenshots
• OS: Windows 11
• Theme: Twenty Nineteen 3.4, as it is in trunk

Steps taken

• Create a new post.
• Add a title, and enable comments.
• Add H1 and H2 headings, or even all heading levels.
• If using Heading blocks, copy all blocks and set additional headings to Align text center and Align text right.
• Publish the post and add an approved comment.
• Copy the headings from the post and paste them in the widget area. Update the widgets.
• Visit the post author's User profile, add Biographical Info for the author of the post, and save changes.
• View the post on the front end. It should look identical before and after applying the patch.
• Create another post with a title.
• Add two heading blocks, both H1 and H2 levels.
• In the Typography settings for each block, show the Decoration options and select Strikethrough.
• While the block is still empty, check whether a line—in the text color—appears in front of the editor's gray "Heading" placeholder text. (It appears before applying the patch but not with the patch.)

Expected results with patch

• ✅ The line pseudo-element continues to display above H1 and H2 headings except for the site title:
  • headings within post and widget content (h1:not(.site-title):before, h2:before)
  • post titles (.entry .entry-title:before)
  • "Published by" heading for the author biography (.author-bio .author-title:before)
  • "Join the Conversation" heading for comments (.comments-area .comments-title-wrap .comments-title:before)
• ✅ The line also continues to align with text when using center and right alignment options.
• ✅ The extra line does not appear in the editor when the heading is still empty and the decoration option is selected.

Screenshots with results

This Firefox screenshot shows H1 and H2 headings in post, author bio, comments, and widget areas after applying the patch.

I also made screenshots of H1 and H2 in Chrome and Edge, plus a screenshot with all headings in Firefox.

Within the editor, the extra Strikethrough line no longer appears if the decoration is set before the heading has any text.

Before patch	With patch

Support Content

blocks used for each post: one set with all heading levels, one set with the empty headings

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 65362
GitHub commit: 781803b

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.