@supports simple demo
If the browser supports @supports and text-decoration: underline wavy #c09, the title CSS Master
below will have a pink squiggly line below it. Otherwise, it will be italicized. If the browser does not support text-decoration-style: double, the link below will have a bottom border value of 4px double #0c0. Otherwise it will use text-decoration: underline double #0c0.
The title of the book associated with this demo is CSS Master. It is published by Sitepoint.