supports.js

/*!
{
  "name": "CSS Supports",
  "property": "supports",
  "caniuse": "css-featurequeries",
  "tags": ["css"],
  "builderAliases": ["css_supports"],
  "notes": [{
    "name": "W3C Spec (The @supports rule)",
    "href": "https://dev.w3.org/csswg/css3-conditional/#at-supports"
  }, {
    "name": "Related Github Issue",
    "href": "https://github.com/Modernizr/Modernizr/issues/648"
  }, {
    "name": "W3C Spec (The CSSSupportsRule interface)",
    "href": "https://dev.w3.org/csswg/css3-conditional/#the-csssupportsrule-interface"
  }]
}
!*/
define(['Modernizr'], function(Modernizr) {
  var newSyntax = 'CSS' in window && 'supports' in window.CSS;
  var oldSyntax = 'supportsCSS' in window;
  Modernizr.addTest('supports', newSyntax || oldSyntax);
});