[trunk] appstyle-dark.css makes no distinction between active and disabled buttons
Steps to reproduce bug
1. File > New
2. Look at the Finish button
Expected behavior: The Finish button is disabled on the first wizard screen. It should look like it is disabled.
Actual behavior: The Finish button looks identical to the active buttons (Next and Cancel)
MuseScore version: r. 3570 trunk, self-built
(Operating System: Windows 7)