<!DOCTYPE html>#DIV1{height: 200px;width: 200px;margin: auto;border: 1px solid black;}#DIV2{width:150px;height:150px;border: 1px solid black;background-color: coral;transform: rotate(45deg);-ms-transform: rotate(45deg); /* IE 9 */-webkit-transform: rotate(45deg); /* Opera、Chrome 和 Safari */}#DIV2original{position:absolute;width:150px;height:150px;border: 1px dashed grey;background-color: lightgrey;opacity:0.5;}