I Love CSS. What Technology should i learn next?

So for context, I'm studying for a while now and I feel pretty comfortable with React, Javascript, Html and CSS.

I love styling pages with pure CSS, its almost therapeutic, but as I understand that's not the industry standard and isn't very efficient.

From from the available CSS technologies that are most commonly adopted (SCSS, SASS, Bootstrap, Tailwind, etc) Which one is the most similar to regular CSS that I can learn and would help me in my career?