SASS vs CSS
Sass is a preprocessor, which adds a number of advancements to CSS. Here is a short article explaining the basics https://sass-lang.com/guide. Notable features:
- preprocessed variables
- parials and imports
- computation
- nesting and &
CSS custom variables
CSS custom variables is relatively new comparing to preprocessor variables like SASS variables. A few advantages:
- not like preprocessor variables, which are static after page load. CSS variables are dynamic and modifiable by media query, or even JS.
A comparison between the two:https://css-tricks.com/difference-between-types-of-css-variables/#article-header-id-0
Theming is one major use case for CSS variables. https://css-tricks.com/css-custom-properties-theming/
