A guide about Web Typography & optimising readability.   http://anartfulscience.com/Typography-First.php

A one-page questionnaire to help your team establish effective frontend guidelines, so that you can write consistent & cohesive code together by Brad Frost.   https://github.com/bradfrost/frontend-guidelines-questionnaire

CSS Architecture for Design Systems by Brad Frost - rules and tricks for large CSS projects   http://bradfrost.com/blog/post/css-architecture-for-design-systems/