.box{  background-color:orange;  width:150px;  height:200px;  border-radius:15px;  display:flex;  box-shadow:0 0 5px #000;  justify-content:center;  flex-wrap:wrap;  align-content:center;  flex-direction:row;  align-items:center;}.item{  background-color:#000;  width:20px;  height:20px;  border-radius:15px;}

实现水平垂直居中