1. BEM – Block, Elment & Modifier
Block Element Modifier is a methodology, that helps you to achieve reusable components and code sharing in the front-end. It is a highly useful, powerful and simple naming convention to make your front-end code easier to read and understand, easier to work with, easier to scale, more robust and explicit and a lot more strict.
2. OOCSS – Object-Oriented CSS
OOCSS is built on top of reset and fonts from the YUI libraries. These libraries provide a common starting point across different navigators.
3. SMACSS – Scalable and Modular Architecture for CSS
SMACSS (pronounced “smacks”) is more style guide than rigid framework. There is no library within here for you to download or install. SMACSS is a way to examine your design process and as a way to fit those rigid frameworks into a flexible thought process. It is an attempt to document a consistent approach to site development when using CSS. And really, who isn’t building a site with CSS these days?!
4. SUIT CSS – Style tools for UI components
SUIT CSS is a reliable and testable styling methodology for component-based UI development. A collection of CSS packages and build tools are available as modules. SUIT CSS plays well with React, Ember, Angular, and other component-based approaches to UI development.
Atomic CSS is a library with a CSS style guide for using atomic CSS in conjunction with OOCSS and CSS components.