text: (function (doc, win) {
    var docEl = doc.documentElement,
      isIOS = navigator.userAgent.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/),
      dpr = isIOS ? Math.min(win.devicePixelRatio, 3) : 1,
      dpr = window.top === window.self ? dpr : 1, //被iframe引用时，禁止缩放
      dpr = 1,
      scale = 1 / dpr,
      resizeEvt = "orientationchange" in window ? "orientationchange" : "resize";
    docEl.dataset.dpr = dpr;
    var metaEl = doc.createElement("meta");
    metaEl.name = "viewport";
    metaEl.content = "initial-scale=" + scale + ",maximum-scale=" + scale + ", minimum-scale=" + scale;
    docEl.firstElementChild.appendChild(metaEl);
    var recalc = function () {
      var width = docEl.clientWidth;
      if (width / dpr > 750) {
        width = 750 * dpr;
      }
      // 乘以100，px : rem = 100 : 1
      docEl.style.fontSize = 100 * (width / 750) + "px";
    };
    recalc();
    if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt, recalc, false);
  })(document, window);
  