Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser.

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a JavaScript library allowing you to use CSS3 & HTML5 while maintaining control over unsupported browsers

Modernizr tests which native CSS3 and HTML5 features are available in the current UA and makes the results available to you in two ways: as properties on a global Modernizr object, and as classes on the <html> element. This information allows you to progressively enhance your pages with a granular level of control over the experience.
Modernizr has an optional (not included) conditional resource loader called Modernizr.load(), based on Yepnope.js ( To get a build that includes Modernizr.load(), as well as choosing which tests to include, go to
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Modernizr is dual-licensed under the BSD and MIT licenses.

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