三栏布局

<div className="main">
    <div className="left">left</div>
    <div className="center">center</div>
    <div className="right">right</div>
</div>

.main {
  display: flex;
  height: 400px;
}

.left,
.right {
  width: 100px;
  background-color: #1890ff;
}

.center {
  flex: 1;
  background-color: #bae7ff;
}