Room list resizer remains in hover state after cursor leaves the window

### Steps to reproduce

1. Hover over the room list resizer
2. Wait until it grows thicker due to being hovered
3. Without moving your cursor out of the bounds of the room list resizer, move the cursor to the edge of the window, then out of the window

### Outcome

#### What did you expect?

Room list resizer is no longer in its thicker hover state

#### What happened instead?

Room list resizer remains in its thicker hover state until I move my cursor back into the window:

https://github.com/user-attachments/assets/c764c973-b8dd-4871-ba80-31f4254b3980

### Operating system

NixOS 26.05

### Browser information

Firefox 152.0.5

### URL for webapp

develop.element.io

### Application version

Element version: df7924df02b0-js-ebb80a936092 Crypto version: Rust SDK 0.18.0 (16a138b), Vodozemac 0.10.0

### Homeserver

Not relevant

### Will you send logs?

No