See this best practices document for components:
https://helpx.adobe.com/experience-manager/using/best-practices-cq-component-design.html
"Do not define CSS styling in components. This practice keeps components loosely coupled from a styling standpoint and lets you restyle them whenever necessary"
Note that component styling is done in CSS - not a config file. You can place CSS in various repository locations. That way - when you want to modify style - update the CSS.