A CSS Framework has many advantages.
With a framework, you get to get your feet wet on how CSS works without having to start from scratch. By using a good framework, you can be much more productive and improve your workflow.
You can save a lot of time with some CSS frameworks because they already have pre-made grids. The grids help you develop coherence in your work.
The frameworks assist construct cross-browser compatible websites that help you operate effortlessly across browsers.