The rem font-size unit is similar to em, only instead of cascading it’s always relative to the root (html) element (more information). This has pretty good modern browser support, it’s just IE 8 and down we need to provide px fallbacks for. Instead of repeating ourselves everywhere, we can use a LESS or SASS mixins to keep it clean. These mixins assumes: html { font-size: 62.5%; /* Sets up the Bas