% - Defines a measurement as a percentage relative to another value, typically an enclosing element.cm Defines a measurement in centimeters. div {margin-bottom: 2cm;}
em - A relative measurement for the height of a font in em spaces. Because an em unit is equivalent to the size of a given font, if you assign a font to 12pt, each "em" unit would be 12pt; thus, 2em would be 24pt.
ex - This value defines a measurement relative to a font's x-height. The x-height is determined by the height of the font's lowercase letter x.
in - Defines a measurement in inches.
mm - Defines a measurement in millimeters.
pc - Defines a measurement in picas. A pica is equivalent to 12 points; thus, there are 6 picas per inch.
pt - Defines a measurement in points. A point is defined as 1/72nd of an inch.
px - Defines a measurement in screen pixels.
