移动端简易版的初始化根元素字体大小

[XZZ22]

(function () {
  var html = document.documentElement;
  function onWindowResize() {
    html.style.fontSize = html.getBoundingClientRect().width / 20 + 'px';
  }
  window.addEventListener('resize', onWindowResize);
  onWindowResize();
})();