CSS frameworks such as Bootstrap and Foundation help developers by reducing the need to code things that have already been done before. Think avoiding the need to reinvent the wheel.
However, learning to code a basic CSS layout is still essential for every web developer especially front-end developers. Knowing the basics is always a good thing because there might be instances where the project requires heavy customization to the applied CSS framework. So with all that said, why not…
You might also want to check out Getting Started with Sass, where we guide you on the powerful CSS pre-processor.