思路是在需要加半圆的元素上加before和after伪元素
xxx::before{
z-index: 1;
width: 12px;
height: 10px;
content: " ";
top: 106px;
position: absolute;
left:-5px;
display: block;
background: rgba(248, 248, 248, 1);//背景色
border-radius: 36px 36px 0 0;
box-shadow: -2px 7px 10px inset rgba(0, 0, 0, 0.03);
transform: rotate(90deg);
}