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font-size-adjust

By Jennifer Kyrnin, About.com

font-size-adjust Description:

The font-size-adjust property allows you to make alternative fonts more legible by adjusting the ratio of their font size to their x-height. The higher this value is (in general) the more legible the font will be at smaller sizes.

font-size-adjust in CSS Versions:

font-size-adjust Syntax:

font-size-adjust: <number> | none | inherit

  • number
    the aspect value, usually of your first choice font. This is then applied to second choice fonts as a scaling factor using the following formula:
    y * (a/a') = c
    • y = the font-size of your first choice font
    • a = the aspect value or number in the font-size-adjust property
    • a' = the aspect value of the available font
    • c = the font-size to apply to the available font
  • none
    Do not preserve the font's x-height.
  • inherit
    The element should have the same font-size-adjust setting as the parent.

font-size-adjust Initial Value:

none

font-size-adjust Applies To:

All elements.

font-size-adjust Inheritance:

This property is inherited.

font-size-adjust Browser Support:

None

font-size-adjust Examples:

If 14px Verdana (with an aspect value of 0.58) was unavailable and an available font had an aspect value of 0.46, the font-size of the substitute would be 14 * (0.58/0.46) = 17.65px. (from W3C)

font-size-adjust Special Notes:

  • The legibility of a font is dependant on more than the font-size but also on the relationship between the size and the x-height.
  • The higher the aspect value is, the more legible a font will be at smaller sizes.
  • Font substitution that relies on font-size alone may rapidly render a page illegible.
  • Compare the images on this page and you will see how different fonts look with adjusted aspect values. (You may need to scroll.)

More font-size-adjust Information

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