Closes #50587 

Before you mark this PR as ready for review, make sure that you have:
- [x] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [x] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:
- Fixed issue that showed underline and strikethrough when markdown
preview screen was scaled to a smaller size


Previously:

<img width="741" height="457" alt="image"
src="https://github.com/user-attachments/assets/f127cf44-c679-4140-b246-e0756c9fca32"
/>



Now:

<img width="742" height="592" alt="image"
src="https://github.com/user-attachments/assets/a29fdc24-cac0-438f-8538-4e85c4df995a"
/>

---------

Signed-off-by: Pratik Karki <pratik@prertik.com>
Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>