The CSS toolkit and guidelines that power GitHub.



Primer is the basecoat of GitHub, made by nerds just like you who share a passion for HTML and CSS. Available for use under the MIT license and built with open source projects like SCSS, Jekyll, Grunt, and more. Includes a small Gruntfile for compiling our SCSS, Autoprefixer for vendor prefixes, and Parker for CSS stats.

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Further Readings

Find out more on the design system and get to know it better.

Primer CSS Styleguide

by Jon Rohan

Primer is GitHub’s internal styleguide and css toolkit. It is used as a way to share buttons, forms, grids, tooltips and more with all the internal.. Read more


by GitHub

Learn more about this styleguide, particularly how it’s built and who maintains it. Primer is GitHub’s internal CSS framework. It includes basic global.. Read more

Redesigning GitHub’s Help..

by Justin M

As a case study, I conducted an audit of GitHub’s current help pages. My goal was to improve usability and accessibility. While rethinking the information.. Read more