[Screen Reader][Firefox] Narrator focus outline does not fully cover block items and End block group

Describe the bug
When using Windows 11 Narrator in Firefox, the screen reader focus (blue outline) does not fully cover the focused block item in the toolbox or the End block group in the workspace during keyboard navigation.

Steps to reproduce the behavior:

1. Enable Windows 11 Narrator.
2. Navigate to Microsoft MakeCode for micro:bit.
3. Open any existing Blocks project.
4. Press Ctrl + B to open the global area menu.
5. Press 3 to move focus to the toolbox.
6. Press Caps Lock + Space to turn off scan mode.
7. Use Arrow keys (Right/Down) to navigate block items (e.g., Basic category).
8. Observe the Narrator focus outline.
9. Use Tab / Down Arrow to navigate to the End block group in the workspace.
10. Observe the Narrator focus outline.

Actual behavior
The Narrator focus outline does not fully cover the focused block item or End block group in Firefox.

Expected behavior
The Narrator focus outline should fully cover the focused element (block item and End block group), consistent with behavior in other browsers.

Screen Recording
https://github.com/user-attachments/assets/1303b7d0-33ba-4d24-bd07-8221a0f196b2

Additional context
1.OS: Windows 11 25H2
2.Browser: Firefox
3.makecode.microbit.org version: 8.1.25
4.Microsoft MakeCode version: 12.3.20

Start by reproducing the issue in Firefox with Windows 11 Narrator, following the listed toolbox and workspace keyboard steps. Compare the focused block item and End block group with other browsers; done means the Narrator focus outline fully covers both elements during keyboard navigation.