SCSS

UnderStrap builds its CSS using SCSS files as Source-files. You can use any SCSS Processor to generate the CSS.

Using SCSS with Gulp

UnderStrap´s built in Workflow supports several Gulp Tasks to automatically build and optimize the CSS.

Feel free to use any SCSS Processor though.

Using other SCSS Processors

There is a good amount of other Desktop and Online SCSS Processors available. Without claiming to be exhaustive, here are some examples:

• CodeKit (Mac only)
• Koala (Windows / Mac / Linux)
• Sassmeister- The SASS Playground (Online Tool)
• PrePros (Windows / Mac / Linux)

For almost any up-to-date Editor like Atom, Brackets, Sublime Text, Visual Studio Code and the likes are either built-in compiling options or additional Plugins available.