Detecting which font was used in a web page Suppose I have the following CSS rule in my page: body { font-family: Calibri, Trebuchet MS, Helvetica, sans-serif; } How can I detect which one of the defined fonts was used in the user's browser? Edit for people wondering why I want to do this: The font I'm detecting contains glyph's that are not available in other fonts and when the user does not have the font I want to display a link asking the