in static/assets/js/modernizr.js [592:603]
tests['opacity'] = function() {
// Browsers that actually have CSS Opacity implemented have done so
// according to spec, which means their return values are within the
// range of [0.0,1.0] - including the leading zero.
setCssAll('opacity:.55');
// The non-literal . in this regex is intentional:
// German Chrome returns this value as 0,55
// github.com/Modernizr/Modernizr/issues/#issue/59/comment/516632
return (/^0.55$/).test(mStyle.opacity);
};