Modernizr detects which HTML5 and CSS3 features user’s browser supports and reports them in a very convenient way: it adds classes to the body tag. The supported features can be checked with javascript, but reporting features with CSS classes is ingenious! Developer don’t have to write if…else -conditions all over javascript because validation can be done in the stylesheet.
Jatka lukemista ”Very handy HTML5 & CSS3 checker: Modernizr.js”