Webmaster in a Nutshell, Third Edition

Style Properties

At the heart of the CSS specification are 53 properties that let you control how the styles-conscious browser presents your documents to the user. The standard collects these properties into six groups: fonts, colors and backgrounds, text, boxes and layout, lists, and tag classification. You’ll find a summary of the style properties later in this chapter.

Property Values

There are five distinct kinds of property values: keywords, length values, percentage values, URLs, and colors.

Keyword property values

A property may have a keyword value that expresses action or dimension. For instance, the effects of underline and line-through are obvious property values. And you can express property dimensions with keywords like small and xx-large. Some keywords are even relational: bolder, for instance, is an acceptable value for the font-weight property. Keyword values are not case-sensitive: Underline, UNDERLINE, and underline are all acceptable keyword values. Keywords also cover such properties as font-family names.

Length property values

So-called length values (a term taken from the CSS standard) explicitly state the size of a property. They are numbers, some with decimals, too. Length values may have a leading + or - sign to indicate that the value is to be added to or subtracted from the immediate value of the property. Length values must be followed immediately by a two-letter unit abbreviation—with no intervening spaces.

There are three kinds of length-value ...