window.onload = function() {
	getRem(750, 100)
};
window.onresize = function() {
	getRem(750, 100)
};

function getRem(pwidth, prem) {
	var html = document.getElementsByTagName("html")[0];
	var oWidth = document.body.clientWidth || document.documentElement.clientWidth;
	html.style.fontSize = oWidth / pwidth * prem + "px";
}