移动端适配

根据窗口大小动态计算字体大小

 function computed() {
        let HTML = document.documentElement,
          deviceW = HTML.clientWidth,
          designW = 750,
          ratio = deviceW / designW * 100;
        if (deviceW >= 410) ratio = 410 / designW * 100;
        HTML.style.fontSize = ratio + 'px';
      }
      computed();
      window.addEventListener('resize', computed);