我想要平滑地移动我的具有多种颜色的渐变，但问题是动画不平滑。它只是在每一步中改变位置。

<style>
  .animated {
    width: 300px;
    height: 300px;
    border: 1px solid black;
    animation: gra 5s infinite;
    animation-direction: reverse;
    -webkit-animation: gra 5s infinite;
    -webkit-animation-direction: reverse;
    animation-timing-function: linear;
    -webkit-animation-timing-function: linear;
  }
  
  @keyframes gra {
    0% {
      background: -webkit-gradient(linear, left top, right bottom, color-stop(0%, #ff670f), color-stop(21%, #ff670f), color-stop(56%, #ffffff), color-stop(88%, #0eea57));
      background: -webkit-linear-gradient(-45deg, #ff670f 0%, #ff670f 21%, #ffffff 56%, #0eea57 88%);
      background: linear-gradient(135deg, #ff670f 0%, #ff670f 21%, #ffffff 56%, #0eea57 88%);
    }
    50% {
      background: -webkit-gradient(linear, left top, right bottom, color-stop(0%, #ff670f), color-stop(10%, #ff670f), color-stop(40%, #ffffff), color-stop(60%, #0eea57));
      background: -webkit-linear-gradient(-45deg, #ff670f 0%, #ff670f 10%, #ffffff 40%, #0eea57 60%);
      background: linear-gradient(135deg, #ff670f 0%, #ff670f 10%, #ffffff 40%, #0eea57 60%);
    }
    100% {
      background: -webkit-gradient(linear, left top, right bottom, color-stop(0%, #ff670f), color-stop(5%, #ff670f), color-stop(10%, #ffffff), color-stop(40%, #0eea57));
      background: -webkit-linear-gradient(-45deg, #ff670f 0%, #ff670f 5%, #ffffff 10%, #0eea57 40%);
      background: linear-gradient(135deg, #ff670f 0%, #ff670f 5%, #ffffff 10%, #0eea57 40%);
    }
  }
</style>
<div class="animated">
  <h1>你好</h1>
</div>

是否可以在不使用jQuery的情况下实现？

我的jsfiddle链接是 https://jsfiddle.net/bAUK6