Design Principles - An open source repository of design principles and methods
Design for Humans - An email course about emotional design
Facebook Design Resources - A collection of free resources made by designers at Facebook
Simple Grid - Responsive & lightweight CSS grid for your website.
Facebook - Connect with friends, family and other people you know. Share photos and videos, send messages and get updates.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.