Using too many font sizes and styles at the same time can easily ruin a layout. Typographic scaling consists of a limited set of font sizes that fit well within the layout structure. The most basic set of styles is based on typographic scaling of 12, 14, 16, 20 and 34 point fonts.
These sizes and styles balance content density and reading comfort in classic applications. Font size is specified through SP (scaleable pixels), allowing larger font sizes to be better accepted.