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CSS CSS Basics (2014) Understanding Values and Units Rem Units

Routine Poutine
Routine Poutine
26,050 Points

If REM is root and EM is parent, is the root a constant and a parent relative -- is the root always 16px?

Hi, a little confused here. Is the root element fixed or customized? Thanks, Matt

1 Answer

Steven Parker
Steven Parker
231,275 Points

REM has a default size based on the browser, though it's nearly always the same. But it's not a constant, you can always change it in CSS or JavaScript code. Think of it as a "document-wide variable".

You might enjoy this blog post with facts and uses for REM. It's called There’s more to the CSS rem unit than font sizing.