<main>
  <h1>在这个区域内滚动鼠标</h1>
</main>

main {
  display: block;
  height: 1000vh;
  text-align: center;
  line-height: 100vh;
}
body{
  background: linear-gradient(to right top, #0089f2 50%, #DDD 50%);
  background-size: 100% calc(100% - 100vh);
  
  &:before {
	  content: '';
	  position: fixed;
	  top: 5px;
	  bottom: 0;
	  width: 100%;
	  z-index: -1;
	  background: white;
	}
}