(function flexible(window, document) {
  var docEl = document.documentElement;

  var dpr = window.devicePixelRatio || 1;

  // adjust body font size

  function setBodyFontSize() {
    if (document.body) {
      document.body.style.fontSize = 12 * dpr + "px";
    } else {
      document.addEventListener("DOMContentLoaded", setBodyFontSize);
    }
  }

  setBodyFontSize();

  // set 1rem = viewWidth / 10

  // var isPhone =
  //   /phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone/i.test(
  //     navigator.userAgent
  //   );
  // if (isPhone) {
  //   alert("移动端");
  // } else {
  //   alert("PC端");
  // }

  function setRemUnit() {
    var rem = docEl.clientWidth / 76.8; //这里默认是10等分的，手动改为24，这个时候1rem=1920px (设计稿的宽为1920px)/24px=80px       (第二点的值的由来)
    docEl.style.fontSize = rem + "px";
  }

  setRemUnit();

  // reset rem unit on page resize

  window.addEventListener("resize", setRemUnit);

  window.addEventListener("pageshow", function (e) {
    if (e.persisted) {
      setRemUnit();
    }
  });

  // detect 0.5px supports

  if (dpr >= 2) {
    var fakeBody = document.createElement("body");

    var testElement = document.createElement("div");

    testElement.style.border = ".5px solid transparent";

    fakeBody.appendChild(testElement);

    docEl.appendChild(fakeBody);

    if (testElement.offsetHeight === 1) {
      docEl.classList.add("hairlines");
    }

    docEl.removeChild(fakeBody);
  }
})(window, document);