What is Pure CSS?
Pure CSS is owned by the YUI (Yahoo User Interface) team. It is open source, and at the time of writing, still early in the development process, the current version is 0.2.0. What Pure CSS aims to do is bring a set of CSS classes to aid in the development of grid, and responsive grid websites, provide a number of classes to easily create common user interface elements (menus and forms), and produce a set of styles to create nice looking buttons, tables and more.
Pure has a very nice graphic look to it. It focuses on being clean, flat, and uncomplicated. Combining this with some lightweight fonts creates a very modern look to a website, fitting in with the latest design trends. Clean, narrow, lightweight lines, and plenty of padding produce an elegant design, that is very pleasing to use.
When would I use Pure?
What Pure is good at is providing a responsive grid. This responds nicely with elements dropping below others at smaller screen sizes based on the proportion of the grid each element takes up. The grid is also incredibly easy to use. Pure CSS uses proportions of the screen size rather than number of columns to cover. A class such as pure-u-1-6 would take up 1/6th of the screen width, and pure-u-2-5 2/5ths of the screen width. Useful indeed as you can create any form of combination of fractions. Every fraction up to 1/24th is covered with a class.
Menus are also a breeze. A simple <ul> with a class of pure-menu does the hardwork, and pure-menu-open will make sure the menu stays open (rather than being a drop down). Useful helper classes are also provided for menu headers, separators, and nested menus. Further to this, it is easy to create a horizontal menu from a vertical one by just adding pure-menu-horizontal , everything else just adapts. Tables and forms are not left out. They both keep the same form of elegance, with minimal effort in the markup. To see all the examples, check out the Pure CSS website.
Why should I use Pure CSS?
Pure is elegant, simple, and lightweight. It is a dream to work with. The beauty of Pure CSS is it is built to be extensible. You can simply add a few styles in your own CSS and change the look to your website. YUI have even provided a tool, Skin-builder, just for this. It gives you a large number of options to change the padding, and colors in your scheme. You can also set to include or exclude specific elements. This will mean you can benefit from the basic set of styles, without looking like a clone of other websites doing the same.
Bootstrap or Pure CSS?
I would certainly recommend you try out Pure CSS. It is early in development too, so you can recommend any changes to the guys behind the project, they are very helpful and listen. It is also Open Source so you can contribute and help fix any issues you find too! It seems a very exciting project, and could have a great future, so I would urge anyone that is interested to contribute, and join in the discussions, to help provide an excellent UI library built entirely in CSS.