Closes #29532 Fixes case where the markdown background was not rendering correctly. This regression was introduced in https://github.com/zed-industries/zed/pull/26454. <img src="https://github.com/user-attachments/assets/1e64930f-c98e-4042-a20e-46eed03293d6" alt="image" width="400" /> Release Notes: - Fixed an issue where markdown code blocks did not wrap correctly.