CSS3利用box-shadow实现相框效果

<style>
html {
overflow: hidden;
background-color: #653845;
background-image: linear-gradient(45deg, hsla(0,0%,0%,.1) 50%, transparent 50%),
linear-gradient(-45deg, hsla(0,0%,0%,.1) 50%, transparent 50%);
background-size: .25em .25em;
box-shadow: inset 0 0 500px hsla(0,0%,0%,.5);
height: 100%;
padding: 1px;
}

body {
height: 300px;
width: 400px;
margin: -150px -200px;
position: absolute;
left: 50%;
top: 50%;
background: gray url(http://pic17.nipic.com/20111122/6759425_152002413138_2.jpg);
background-size: cover;
border: 1px solid;
border-color: #bbb #999;
box-shadow:
0 2px 5px hsla(0,0%,0%,.4),
inset 0 1px 0 #ccc,
inset 1px 0 0 #aaa,
inset 0 -1px 0 #ccc,
inset -1px 0 0 #aaa,

inset 0 2px 0 #c6c6c6,
inset 2px 0 0 #a6a6a6,
inset 0 -2px 0 #c6c6c6,
inset -2px 0 0 #a6a6a6,

inset 0 3px 0 #c0c0c0,
inset 3px 0 0 #a0a0a0,
inset 0 -3px 0 #c0c0c0,
inset -3px 0 0 #a0a0a0,

inset 0 4px 0 #b9b9b9,
inset 4px 0 0 #999,
inset 0 -4px 0 #b9b9b9,
inset -4px 0 0 #999,

inset 0 5px 0 #b6b6b6,
inset 5px 0 0 #969696,
inset 0 -5px 0 #b6b6b6,
inset -5px 0 0 #969696,

inset 0 6px 0 #b0b0b0,
inset 6px 0 0 #909090,
inset 0 -6px 0 #b0b0b0,
inset -6px 0 0 #909090,

inset 0 7px 0 #a9a9a9,
inset 7px 0 0 #898989,
inset 0 -7px 0 #a9a9a9,
inset -7px 0 0 #898989,

inset 0 8px 0 #a6a6a6,
inset 8px 0 0 #868686,
inset 0 -8px 0 #a6a6a6,
inset -8px 0 0 #868686,

inset 0 9px 0 #a0a0a0,
inset 9px 0 0 #808080,
inset 0 -9px 0 #a0a0a0,
inset -9px 0 0 #808080,

inset 0 10px 0 #888,
inset 10px 0 0 #666,
inset 0 -10px 0 #888,
inset -10px 0 0 #666,

inset 0 0 10px 10px hsla(0,0%,0%,.5);
}
</style>