index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1, minimum-scale=1.0">
    <title>随便写写</title>
  </head>
  <body>
    <div id="app"></div>
    <!-- built files will be auto injected -->
  </body>
  <script>
    //rem 样式适应
    window.onload = function () {
      var t;
      w();
      window.addEventListener("resize", function () {
        clearTimeout(t);
        t = setTimeout(w, 300)
      }, false);
    }
    function w() {
      var r = document.documentElement;
      var a = r.getBoundingClientRect().width;
      if (a > 750) {
        a = 750;
      }
      //750/w = 100/font-size
      rem = a / 7.5;
      r.style.fontSize = rem + "px"
    }
  </script>
</html>