Designing and developing a site can sometimes be exhausting because all the little things that have to be considered, all the tweaks that should be made and all the small modifications that could occur.
This doesn’t necessarily have to be a general rule. Designers and developers are constantly releasing tools to help them at their workflow, tools that everybody can use.
Such tools are represented by CSS libraries which are a time saver for web designers and everyone should use one to have the projects done faster. A list of CSS libraries is in this article, a list of libraries which on Github are the most popular of their kind.
I haven’t added any description to any of these because you deserve more than an excerpt for these libraries and you have to see their whole description.