The syntax of
<dimension> is a
<number> immediately followed by a unit which is an identifier. Unit identifiers are case insensitive.
12px 12 pixels 1rem 1 rem 1.2pt 1.2 points 2200ms 2200 milliseconds 5s 5 seconds 200hz 200 Hertz 200Hz 200 Hertz (values are case insensitive)
12 px The unit must come immediately after the number. 12"px" Units are identifiers and therefore unquoted. 3sec The seconds unit is abbreviated "s" not "sec".
|CSS Values and Units Module Level 3 (CSS Values 3)|
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