This contains all HTML elements, their mark up and basic styling. Each section has a partner .scss file.
Start here. Go through all the partner Sass files, (start with _settings.scss), creating your base styles for the base elements. You can then go about expanding and adding UI elements from your specific design.
N.B. Default layout is full width seen here on the homepage. Add
.layout-sidebar class to body for large screen to have side nav, a la the pages of this styleguide.