Pressing modifier key over tab makes tab change size

[jacobgkau]

As reported here: #490 (review)

If I press Shift while hovering over a tab, the tab gets slightly larger until I either press Shift over a different tab or click somewhere in the app. See the result of pressing Shift over one tab and then the other below:

2026-01-29.12-58-08.mp4

This does not happen if enough tabs are open that the < and > buttons to scroll through them appear.