How to apply mixins and customize colors of Buttons?

I’m trying to create a reusable button component using our brand colors. Couple of questions:
-Why can’t I apply a style mixin to a component? (per this page
-How do I set more (custom) colors as options for button variants?

Components are generally supposed to look consistent, so individual instances of components don’t take styles, aside from positioning. But you can edit the component and apply your mixins within there.

That’s also how you can add more variants or customize them. From the left outline view, at the top, you’ll see a list of all the components in your project. You can use that to navigate to the button component artboards. You can also right click any component instance and open up to that arena as well.