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The following table shows the value types, available values, samples, and some general comments regarding the use of property values within CSS.

Note 

 Not all value types are represented here, only the ones used in this book. There are additional types available for aural style sheets and counters. You can find information on these value types at www.w3.org/TR/REC-CSS2/syndata.html#values.

Value Types

Value Type	Available Values	Example(s)	Notes
Integers and Real Numbers	0-9	line-height: 1.3;	Line-height is the only property that accepts a real number; z-index is the only property to accept integers.
Lengths: Relative Units	Height of M (em) Height of X (ex) Pixels (px)	0.95em 1.0ex 14px	Relative unit lengths are scaled according to the size of the parent element.
Lengths: Absolute Units	Inches (in) Centimeters (cm) Millimeters (mm) Points (pt) Picas (pc)	1in 2cm 2mm 12pt 12pc	Absolute length units do not scale.
Lengths: Keywords	xx-small, x-small, small, smaller, medium, large, larger, x-large, xx-large	font-size: large	Keyword measurements do not necessarily scale. These keywords apply only to font-size.
Percentages	%	width: 100%
URL + URN =	URI url()	url(images/logo.gif)	Single or double quotes maybe used inside the parentheses. You must escape commas, parentheses, whitespace characters, and single and double quotes which appear in a URI with a backslash.
Colors: Keywords	aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, orange, purple, red, silver, teal, white, yellow	color: orange;	Most named colors are not part of the web-safe palette.
Colors: Hexadecimal	#hexvalue	color: #FFFFFF
Colors: Hexadecimal Shorthand	#hexvalue	color: #FFF	Only available for paired values. All web-safe colors can be written in shorthand.
Colors: RGB	#hexvalue	color: (255, 255, 255)
Colors: RGB	%	color: (80%, 30%, 20%)