Support for @supports in Firefox Nightly ∙ Cameron McCormack3 August 2012 Yesterday I landed support for the CSS @supports at-rule for Gecko (based in part on some earlier work done by former intern Vitor Menezes), and it should now be in Firefox Nightly builds. @supports is part of CSS Conditional Rules Module Level 3, and allows authors to condition rules based on whether particular property declarations are supported. For example, let’s say you want to
