How granular are CSS rem units?
<p>I am developing a scalable mobile/desktop friendly website using CSS rem units based on the average viewport size of the site.</p>

<p>I have been setting rem sizes as low as 0.001rem for certain padding and margins, which is working fine in my Firefox browser... but will it work in all modern browsers?</p>

<p>I am only questioning the ability to use 0.001rem units because the highest granularity I have seen prior to thousandths is hundredths of opacity... like <code>opacity:0.25</code> for example.</p>

<p><strong>How low can rem units go?</strong> Is 0.00000001rem an acceptable value in modern browsers?</p>