多层阴影

.box-shadow {
width: 100px;
height: 100px;
margin: 40px;
border-radius: 5px;
box-shadow: 0 0 0 1px red,
0 0 0 5px blue,
0 0 0 8px green,
0 0 0 12px yellow,
0 0 0 16px orange,
0 0 0 20px #06c,
0 0 0 24px lime;
}