Values have the following meanings:

<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 ]

<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 ] 