URL bar highlighting is lost after entering full screen mode

### Describe the bug

After entering full screen, domain isn't highlighted properly anymore, the whole URL is in one single color. It happens the moment you hit F11, even before the UI is fully hidden away. Highlighting can only be regained by clicking inside the URL bar and then somewhere else on the page.

This isn't exactly a new issue, as I remember noticing this for quite a long time.

### Expected behavior

_No response_

### Screenshots

Before entering full screen:


After entering full screen:


### OS

Windows 11

### OS - Others

_No response_

### Firefox Version

120.0

### Distribution

- [X] [Original Lepton](https://github.com/black7375/Firefox-UI-Fix)
- [ ] [Lepton's photon style](https://github.com/black7375/Firefox-UI-Fix/tree/photon-style)
- [ ] [Lepton's proton style](https://github.com/black7375/Firefox-UI-Fix/tree/proton-style)

### Theme

- [X] Light
- [X] Dark
- [X] Alpenglow (System: Light)
- [X] Alpenglow (System: Dark)
- [X] System Default
- [X] Others: (e.g. [Photon Colors](https://addons.mozilla.org/en-US/firefox/addon/photon-colors/), [Google Chrome Dark](https://addons.mozilla.org/en-US/firefox/addon/google-chrome-dark/), [Fairytale Of Nature](https://addons.mozilla.org/en-US/firefox/addon/fairytale-of-nature/))

### Theme - More Info

_No response_

### `user.js` setup

Default Original Lepton.

### Additional context

_No response_

Reproduce the issue on Windows 11 with Firefox 120 by entering full screen with F11 and observing the URL bar before and after the transition. Trace the SCSS responsible for URL bar domain highlighting and verify that the highlighting remains visible after full screen is entered without requiring focus changes.

Written by the indexing model from the issue text.