For many mainstream body text
      fonts, 14 and 18 point is roughly equivalent to 1.2 and 1.5 em or to 120% or 150%
      of the default size for body text (assuming that the body font is 100%), but authors
      would need to check this for the particular fonts in use. When fonts are defined in
      relative units, the actual point size is calculated by the user agent for display.
      The point size should be obtained from the user agent, or calculated based on font
      metrics as the user agent does, when evaluating this success criterion. Users who
      have low vision would be responsible for choosing appropriate settings. Note 4 When using text without specifying the font size, the smallest font size used on major
      browsers for unspecified text would be a reasonable size to assume for the font. If
      a level 1 heading is rendered in 14pt bold or higher on major browsers, then it would
      be reasonable to assume it is large text.