Elemental UI is a flexible and beautiful UI Toolkit for React.js Websites and Apps.
There are modular set of UI scaffolding components and controls for React that are built from the outset to natively implement React patterns.
Draft.js is a framework for building rich text editors in React, powered by an immutable model and abstracting over cross-browser differences.
Material Design is a specification for a unified system of visual, motion, and interaction design that adapts across different devices and different screen sizes.
For developers using AngularJS, Angular Material is the reference implementation of Google's Material Design Specification. This project provides a set of reusable, well-tested, and accessible UI components based on Material Design.
AngularJS lets you write client-side web applications as if you had a smarter browser. It lets you use good old HTML (or HAML, Jade and friends!) as your template language and lets you extend HTML’s syntax to express your application’s components clearly and succinctly.