No configuration provided for compiling the theme

Problem/Motivation

The codebase does not include a configuration file for a tool to compile the scss files into css, and the project documentation → doesn't mention it. As a result it is not clear how someone is supposed to contribute CSS changes to the project.

Steps to reproduce

Try to modify the scss files, there's no indication on how to compile the files to make the changes available in the css files.

Proposed resolution

Provide a configuration for e.g. gulp, and documentation on how to compile the theme.

Remaining tasks

Add a configuration for a scss compiler.
Add documentation on how to use it.

User interface changes

n/a

API changes

n/a

Data model changes

n/a