red 颜色无法显示，div.style.color = 'red'此行代码出现报错

<script src="https://www.imooc.com/static/lib/jquery/1.9.1/jquery.js"></script>

 <script>

          let $div = $('div');

          let div = $div[0];

          div.style.color = 'red';

     </script>

     <div>元素一</div>

     <div>元素二</div>

     <div>元素三</div>