Basecoat is a guide and library of SCSS partials to extend the Primer CSS toolkit for use on non-product websites of GitHub. Its purpose is to help the designers at GitHub efficiently create consistent, well-built, accessible, and on-brand marketing websites.

Browser support

Basecoat currently supports Internet Explorer 9*+ and the latest two versions of Chrome, Safari, and Firefox on OS X and Windows. It was built responsively using mobile-first styles and markup.

* Progressive enhancements for modern browsers, like CSS3 background image gradients, text-shadows, and HTML5 form elements are not supported in IE9. Basecoat is designed with these progressive enhancements in mind, allowing for IE9 to render default content and modern browsers to progressively enhance it.


  • Our styles are written in SCSS.
  • Bower can be used to import other dependencies (namely Octicons, Primer)
  • Grunt is recommended for packaging and deploying styles and JavaScript to production. A small gruntfile is included for compression, minification, and vendor prefixing of styles before they are deployed.


We're thrilled that you want to contribute to this project. A few things to note when opening a PR: