3.4.3 CSS
In the mx-element% method descriptions, “CSS” refers to
the Cascading Style Sheets specification. A CSS length is string
consisting of a decimal integer number followed by one of the units
px (pixels), em (font height), ex
(height of an “x”), in (inches), cm
(centimeters), mm (millimeters), pc (picas), or
pt (points). A CSS percentage is a string consisting of a
decimal real number followed by %. When using
-native methods, CSS lengths and percentages are
given as strings. For use by non-native methods, the
css-percentage and css-length structures have been
defined.