<div class="wrapper">
  <div class="left">
  </div>
</div>
.wrapper {
  width: 800px;
  height: 375px;
  background: #FFEDE0;
  border: 1px dashed red;
  overflow: hidden;
}

.left {
  width: 160px;
  height: 100%;
  background: #FFD1AE;
/*   border-right: 6px solid white; */
  border-radius: 0 20px 20px 0 / 0 50% 50% 0;
  box-shadow: 6px 0 #fff;
}
// 缺点：虽然解决了 border-radius + border 的弧线变形问题，但是弧线的弧度不够圆润

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