Kris 097d987332
UX: add HTML class for composer preview to manage sidebar height (#30956)
This adds the class `composer-has-preview` to the HTML element when the
composer is opened and the preview is visible.

This allows us to adjust the sidebar height, so that the previewless
composer can overlap the sidebar and better utilize the available space.


Before:

![image](https://github.com/user-attachments/assets/8780f159-5d24-4ac0-8a4f-43a9b1665532)



After: 

![image](https://github.com/user-attachments/assets/baf69856-0ece-453f-aa0f-e7be9939af97)
2025-01-23 12:41:36 -05:00
..