CSS frameworks can reach bundle sizes of up to 3.5MB (uncompressed) - often including features and components that will never be used in the design itself. And, other than significant performance improvements, a minimal/lightweight CSS framework is just much easier to work with.
And a great way to learn more about CSS, too.
Link: Minimal CSS Frameworks: 10 Great Choices
And a great way to learn more about CSS, too.
Link: Minimal CSS Frameworks: 10 Great Choices