CSS
Go through the following tutorials and articles to learn CSS.
- CSS Tutorial by W3Schools
- Flexbox Froggy
- CSS Flexbox Fundamentals Visual Guide
- Flexbox — The Animated Tutorial
- Flexbox Defense
- CSS Grid Garden
- Opening the Box Model
- Learn CSS Layout
- Learn BEM — Block Element Modifier
Sass (Syntactically Awesome StyleSheets)
Note: Use SCSS syntax.