Polyfill for vw, vh, vm units. It calcutes the values in px and apply automatically to your css. Credit for Lea Verou (https://gist.github.com/LeaVerou) and Xandor Schiefer (https://gist.github.com/zeorin)

vunits.js

/**
 * Polyfill for the vw, vh, vm units Requires StyleFix from -prefix-free
 * http://leaverou.github.com/prefixfree/
 * 
 * @author Lea Verou
 *
 * Contributor: Xandor Schiefer
 * Contributor: Guto Marrara Marzagão
 *
 */

(function() {

	if (!window.StyleFix) {
		return;
	}

	// Feature test
	var dummy = document.createElement('_').style;
	var units = [ 'vw', 'vh', 'vm' ];

	StyleFix.register(function(css) {
		var w = innerWidth, h = innerHeight, m = Math.min(w, h);

		// For help with this regex: see debuggex.com, then input: (/\*)?(-?\d+(\.\d+)?)(vw|vh|vm)(\*/)?(-?\d+(\.\d+)?px)?
		var regex = '(/\\*)?(-?\\d+(\\.\\d+)?)(' + units.join('|')	+ ')(\\*/)?(-?\\d+(\\.\\d+)?px)?';

		return css.replace(RegExp(regex, 'gi'), function(match, notUsed1, originalValue, notUsed2, unit, notUsed3, notUsed4, notUsed5) {
			switch (unit) {
			case 'vw':
				var newValue = originalValue * w / 100;
				break;
			case 'vh':
				var newValue = originalValue * h / 100;
				break;
			case 'vm':
				var newValue = originalValue * m / 100;
				break;
			}
			return '/*' + originalValue + unit + '*/' + newValue + 'px';
		});
	});
	
	var styleFixResizeTimer;

	window.addEventListener('resize', function () {
		if (typeof styleFixResizeTimer !== 'undefined')
			clearTimeout(styleFixResizeTimer);

		styleFixResizeTimer = setTimeout(function () {
				StyleFix.process();
		}, 200);
	}, false);

})();