Is there a guide on the web on how to customize css in ionic 1.x?

I’ve been searching all over the web but it seems that most tutorials just shows how I can change a variable value within sass. I want to know the proper way of styling using sass and it would be nice if I can get some examples…
For example, if i want to create my custom design, how should I do this? should I work directly within sass??

If you know any link that would be nice! to learn to practice online