How to Create Multiple Borders in CSS3
非常酷的方式創建box陰影，允許你創建多個邊框
box-shadow:
0 0 0 2px #000,
0 0 0 3px #999,
0 0 0 9px #fa0,
0 0 0 10px #666,
0 0 0 16px #fd0,
0 0 0 18px #000;