To use lesshat, you need node/npm installed then run npm install lesshat --save to install and save lesshat into your package.json. From here, you just need to reference the node_modules/lesshat/lesshat.less within your .less stylesheets. Why lesshat? In August 2012, while we were developing and extending CSS Hat for LESS we needed universal mixins. Unfortunately, none of available were good enough that would satisfy our needs and that’s why we created new custom ones on our own, which have become the most popular mixin library for the whole LESS CSS.