Author: aishoodame
Description:
# Sizing fonts and sizing by font metrics
The only way the WWW author has to know the what size of type is well readable by a user is the default size selected by the user. When a font is displayed at a size smaller than the user's default font size, that creates a usability and accessibility problem. This is more widespread a problem than only affecting those who's eyesight is so poor that they count as disabled.
Screen resolution, in the sense of dots per inch (DPI), will determine how much space on the display a glyph occupies, making measurements in pixels (px) an especially ineffective unit to use in specifying typeface size.
Units and methods for typeface sizing
Relevant information about the
CSS properties is at https://www.w3.org/TR/2009/CR-CSS2-20090908/fonts.html#font-size-props
See also:
Chapter 4 : The amazing em unit and other best practices
The Wikipedia entry on em is illuminating.
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