Should I define CSS margins in pixels or ems? Why? When?

TunnelOfMath

New Member
We have a CSS file with some rules similar to the following:\[code\].directory-result ul{ margin-top: 20px; width: 60em;}.about-text{ margin-top: 1em; margin-bottom: 1em;}\[/code\]Everything is working ok, but we're wondering specifically about the inconsistencies between the margin-top values. One is 20px and the other is 1em.Which is the best one to go with? What are the points I should consider when deciding which to use? Thanks.
 
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