The format of a percentage value is an optional sign character ('+' or '-', with '+' being the default) immediately followed by a number (with or without a decimal point) immediately followed by '%'.

Percentage values are always relative to another value, for example a length unit. Each property that allows percentage units also defines what value the percentage value refer to. Most often this is the font size of the element itself:

For example :

P { line-height: 120% }

120% of the element's 'font-size'

In all inherited CSS1 properties, if the value is specified as a percentage, child elements inherit the resultant value, not the percentage value.

© 1995-1998, Stephen Le Hunte