Less provides the following mechanisms: variables, nesting, mixins, operators and functions; the main difference between Less and other CSS precompilers is that Less allows real-time compilation via less.js by the browser.

Functions map one-to-one with JavaScript code, allowing manipulation of values.

[6][3] Sass was designed to both simplify and extend CSS, so things like curly braces were removed from the syntax.

[7] The newer versions of Sass also introduced a CSS-like syntax called SCSS (Sassy CSS).

One option is to include the less.js JavaScript file to convert the code on-the-fly.