Adrian Sandu explains the purpose and advantages of rem units, demonstrating ways to use em and rem units in CSS layouts.
https://www.sitepoint.com/understanding-and-using-rem-units-in-css/
* W3C spec
* Font sizing with REM
* his own take on the use of rem units
* A third view
* The Power of em Units in CSS
* One Method for Using ems and rems in CSS
* @SitePoint
* CodePen
* Bootstrap 4
* Material Design
* Material-UI
* Every Layout
* Size Matters: Balancing Line Length And Font Size In Responsive Web Design
* media query spec
* View Media Query Demo on CodePen
* Zurb Foundation
* use relative units for text sizing
* empirical study run by the people behind the Internet Archive
* Using rem Units for Scaling Documents Demo #1
* Dynamic Sizing of Modules with Rem Units
* @SitePoint
* CodePen