<!doctype html> <html lang="en"><!-- The lang is important! --> <meta charset="utf-8"> <title>CSS Test: Calc with rem and relative units on the root element</title> <link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io"> <link rel="help" href="https://drafts.csswg.org/css-values/#rem"> <link rel="help" href="https://drafts.csswg.org/css-values/#funcdef-calc"> <link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1431031"> <link rel="match" href="calc-rem-lang-ref.html"> <style> html { font-size: calc(1rem + 1em); } </style> <p style="font-size: initial">You should see a green box twice-the-initial-font-size wide.</p> <div style="width: 1em; height: 1em; background: green;"></div> </html>