Update the diff collapse button for dark mode.
Review Request #13763 — Created April 22, 2024 and submitted — Latest diff uploaded
In light mode, the diff collapse button retains the styling we had
before. However, in dark mode, it takes on a Primary Button appearance.
This helps it stand out better against the dark background.Some effort was put into just using a button styling across the board,
but ultimately I decided not to affect the light mode appearance too
much at this stage.
Tested on light and dark mode.