径向渐变现在在一个实现混乱，Safari不支持椭圆径向背景，所以支持Safari即将推出）。 Chrome有这么多版本，我不知道它，IE9不支持它们。

Radial gradients are in an implementation mess right now, Safari doesn't support elliptical radial backgrounds (Webkit Nightly does, so support for Safari is coming soon). Chrome has so many versions I'm not sure about it, and IE9 doesn't support them.

所以我想说你***的选择是通过inset盒阴影：

So I'd say your best option is faking it through inset box shadows:

.shadow {
  height: 80px;
  box-shadow: inset 0 75px 75px #fff, 
              inset 0 50px 50px #fff,
              inset 0 20px 20px #fff,
              inset 0 5px 5px #fff;

  background: #ccc;
}

http://jsfiddle.net/nmtHf/