在public下的index.html中添加如下js代码

fnResize();
window.onresize = function () {
  fnResize();
}
function fnResize() {
  var deviceWidth = document.documentElement.clientWidth || window.innerWidth;
  if (deviceWidth >= 560) {
      deviceWidth = 560;
  }
  var wr;
  var rem;
  if (deviceWidth == 375) {
     rem = 100
  } else {
    wr=deviceWidth / 375;
    rem=wr * 100;
  }
                        
  document.documentElement.style.fontSize = rem + 'px';
}

执行命令行npm run serve（vue-cli4）