<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=504275) </details> <!--IssueSummary end--> ### Summary When using the Syntax Highlighting Light Theme and the Monokai Theme, certain code elements can appear as if they’ve been removed. This issue happens because a `span` with the `err` class wraps around specific characters, like the `@` symbol. This styling makes it confusing during code reviews, as it may seem that elements are missing or improperly highlighted. In other syntax themes, the `@` symbol is also wrapped with a `span` using the `err` class, but it isn’t highlighted in red, unlike in the Light and Monokai themes. ### Steps to reproduce 1. Open a MR that includes characters such as `@` (for example: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/172280). 2. Go to Settings > Preferences > Appearance 3. Select either the `Light` or the `Monokai` theme for syntax highlighting 4. Refresh the MR page to make sure it’s displaying with the selected Syntax Highlighting Theme. 5. Observe that the `@` symbol appears as if it’s removed. ### What is the expected *correct* behavior? The `@` symbol and similar characters should display consistently across all syntax highlighting themes. In the Light and Monokai themes, the `@` symbol should not appear red or look broken/removed. Instead, it should retain a neutral color that matches its display in other themes, ensuring it is easily visible and does not seem removed or incorrect. ### Relevant logs and/or screenshots #### Light Theme  #### Monokai Theme  This bug happens on GitLab.com <!-- If you don't have /label privileges, follow up with an issue comment of `@gitlab-bot label ~"type::bug"` -->