Action menu should not overlap main content panel

<img width="378" height="361" alt="Image" src="https://github.com/user-attachments/assets/a9fc95f0-f70f-4582-b045-d17ac2516c13" />


Previous UI was using a padding-right to reserve visual space for action-menu.

<img width="461" height="645" alt="Image" src="https://github.com/user-attachments/assets/8cb82a13-e6f7-4e95-85aa-b4370ee3c6c6" />