Sass & Css in Ionic

Is there some documentation by Ionic telling us how to use Sass and Css in ionic ? Is it the same or different ?
Help Is Appreciated.

I dont think Ionic has documentation on CSS and SASS.
Sass is just like a better version of CSS.

These CSS and SASS links might help you.

SASS (Syntactically Awesome Stylesheet) is a CSS pre-processor, which helps to reduce repetition with CSS and saves time. It is more stable and powerful CSS extension language that describes the style of document structurally.