text: (function (doc, win) {
              var docEl = doc.documentElement,
                      resizeEvt = 'onorientationchange' in window ? 'orientationchange' : 'resize',
                      recalc = function () {
                          var clientWidth = docEl.clientWidth;
  
                          if (!clientWidth) return;
  
                          //在375px宽度的屏幕下 1rem = 100px
                          docEl.style.fontSize = 100 * (clientWidth / 375) + 'px';
                      };
  
              if (!doc.addEventListener) return;
  
              win.addEventListener(resizeEvt, recalc, false);
              doc.addEventListener('DOMContentLoaded', recalc, false);
  
  })(document, window);