Font Sizes

<absolute-size>

An <absolute-size> keyword refers to an entry in a table of font sizes computed and kept by the user agent. Possible values are:

[ xx-small | x-small | small | medium | large | x-large | xx-large ]

On a computer screen a scaling factor of 1.2 is suggested between adjacent indexes; if the 'medium' font is 12pt, the 'large' font could be 14.4pt. Different media may need different scaling factors. Also, the user agent should take the quality and availability of fonts into account when computing the table. The table may be different from one font family to another.

Note. In CSS1, the suggested scaling factor between adjacent indexes was 1.5 which user experience proved to be too large.

<relative-size>

A <relative-size> keyword is interpreted relative to the table of font sizes and the font size of the parent element. Possible values are:

[ larger | smaller ]

For example, if the parent element has a font size of 'medium', a value of 'larger' will make the font size of the current element be 'large'. If the parent element's size is not close to a table entry, the user agent is free to interpolate between table entries or round off to the closest one. The user agent may have to extrapolate table values if the numerical value goes beyond the keywords.

<length>

A length value specifies an absolute font size (that is independent of the user agent's font table). Negative lengths are illegal.

<percentage>

A percentage value specifies an absolute font size relative to the parent element's font size. Use of percentage values, or values in 'em's, leads to more robust and cascadable style sheets.