<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;
}
// 圆弧会出现变形的情况

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