Hello,

2) Please check how it works with the default wordpress theme just to check whether the issue is with our theme or not.

3) Please try adding the following Custom CSS in the Global Custom CSS area under Theme Settings >> Custom CSS.

.product-label.onsale {
backgoorund: purple;
}

4) It could not change by itself. As I see the padding is 150px and it’s displayed fine on my end.

Screenshot for Clarification: https://gyazo.com/1c0e96328b45347038f16089c02ab870

Best Regards