Thank You,
Works perfectly, for others who run in the same trouble, a nested class looks like this:
.qa-a-item-buttons .qa-form-light-button-edit{}
Without semicolon in between.
The qa-a-item-buttons class is the class for the buttons in the answer section and the qa-form-light-button-edit class is the class of the edit button. If You use that, dont forget to do the same for the matching hover classes.