带有圆角的边框图像

我有一个 div，它使用线性渐变作为边框图像来给它一些渐变边框

<div class = "gradborders" id="mydiv" runat="server">
..various elements...
</div>
....
....
.gradborders{ 
border-image: -webkit-linear-gradient(45deg, rgba(20,20,20,0.7) 5%,  rgba(90,90,90,0.5) 35%, rgba(255,255,255,0.2) 100%) 8 stretch;
border-image: -o-linear-gradient(45deg, rgba(20,20,20,0.7) 5%,  rgba(90,90,90,0.5) 35%, rgba(255,255,255,0.2) 100%) 8 stretch;
border-image: -moz-linear-gradient(45deg, rgba(20,20,20,0.7) 5%,  rgba(90,90,90,0.5) 35%, rgba(255,255,255,0.2) 100%) 8 stretch;
border-image: linear-gradient(45deg, rgba(20,20,20,0.7) 5%,  rgba(90,90,90,0.5) 35%, rgba(255,255,255,0.2) 100%) 8 stretch;}

我想要圆角。我尝试了标准方法，将其添加到 gradborders 中：

border-radius: 8px;
-webkit-border-radius: 8px; 
-moz-border-radius: 8px;

但没有骰子。我什至尝试在 div 上使用 AJAX 圆角扩展器，我确信它可以工作，但也不起作用。有任何想法吗？？

也许是这样的JSFiddle http://jsfiddle.net/7f3bm/会做：

<div class="container">
    <div class="gradborders">hi</div>
</div>

and

.container{border-radius: 10px;overflow:hidden;}
.gradborders{ 
-webkit-border-image: url("http://photos-f.ak.fbcdn.net/hphotos-ak-ash4/1686_520555094669668_1347475803_n.jpg") 8;}