CSS units have been the subject of several articles here on SitePoint (such as A Look at Length Units in CSS, The New CSS3 Relative Font Sizing Units, and The Power of em Units in CSS). In this article, we increase the count by having an in-depth look at rem units, which have excellent browser support and a polyfill if you need support for old IE. This article was updated in December, 2019 to reflect the current state of rem…