The purpose of this ticket is to create an "npm" package that contains reusable elements for Science Platform websites and applications based on a React and styled-components stack. This package can also be used by the documentation portal (https://github.com/lsst-sqre/www_lsst_io). Specific goals are:

• Encode colours in YAML files in such a way that those colours can be imported/embedded into style sheets or other components.
• Provide a source for reusable base style sheets
• Provide an importable package for styled-components and other common react components.