Bug Report – UI Tabs Shift Upwards After Closing Sidebar Menu

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

Closing any panel opened from the left sidebar (e.g., Models, Workflows) should not affect the page layout. The top workflow tabs should remain fully visible and stay in their original position.

### Actual Behavior

After opening a left-sidebar menu item and then closing it by clicking on the workflow canvas area, the entire page shifts upward. This causes the top workflow tabs to become partially hidden. The shift happens every time this interaction occurs.

### Steps to Reproduce

1. Start ComfyUI or reload the webpage.
2. Observe that the top workflow tabs are displayed normally.
3. Open any menu item from the left sidebar (e.g., Models, Workflows).
4. Close the opened panel by clicking anywhere on the workflow canvas area.
5. Notice that the page layout shifts upward and the top workflow tabs become partially hidden.

### Debug Logs

```powershell
[ComfyUI-Manager] All startup tasks have been completed.
```

### Other

_No response_