<script>
function Rem() {
var docEl = document.documentElement,
oSize = docEl.clientWidth / 7.5;
if (oSize > 100) {
oSize = 100; // 限制rem值 640 / 6.4 =100
}
docEl.style.fontSize = oSize + 'px';
}
window.addEventListener('resize', Rem, false);
Rem();
</script>