Less.js

Less.js is an open source style sheet which is similar to CSS.

Less (Leaner Style Sheets) can speed app web app development with tons of features like CSS extendability, theme, and maintenance. It offers a handful list of function variables, mixins, and some techniques.

In terms of usage, Less looks an operate similarly with CSS. So, learning it would be smooth and easy. The difference between CSS and Less is the addition and integration of more specific functions. Also, it has a full detailed documentation which you can familiarize each function and tools.

Easily understandable variables which are quite useful in day-to-day web development using Less. In addition, Less provide an interesting feature in Mixins. It is a brunch of properties where you can specify one rule-set into another. You can use these properties inside other rule-sets by dropping in the class name. Further, Less can use nesting instead of overly used cascading in CSS.