DIV 弹出层 层的边框是半透明的

<style>
*{margin:0; padding:0; border:0;}
body{ background:#999; }
.wrap{ height:200px; width:200px; top:50%; left:50%; margin:-100px 0 0 -100px; position:absolute; background:none;}
.ground{ background:#EEE; height:100%; width:100%; opacity:.6; filter:alpha(opacity=60); -moz-opacity:.6; -moz-border-radius: 5px;
}
.content{ text-align:center; height:180px; width:180px; top:10px; left:10px; position:absolute; background:#fff; -moz-border-radius: 1px; }
.line{ width:100%; background:#f00; height:4px; top:50%; position:absolute;  font-size:0px;}
</style>
<div class="line" ></div>
<div class="wrap">
  <div class="ground"></div>
  <div class="content">FF下看有漂亮的圆角</div>
</div><style>
*{margin:0; padding:0; border:0;}
body{ background:#999; }
.wrap{ height:200px; width:200px; top:50%; left:50%; margin:-100px 0 0 -100px; position:absolute; background:none;}
.ground{ background:#EEE; height:100%; width:100%; opacity:.6; filter:alpha(opacity=60); -moz-opacity:.6; -moz-border-radius: 5px;
}
.content{ text-align:center; height:180px; width:180px; top:10px; left:10px; position:absolute; background:#fff; -moz-border-radius: 1px; }
.line{ width:100%; background:#f00; height:4px; top:50%; position:absolute;  font-size:0px;}
</style>
<div class="line" ></div>
<div class="wrap">
  <div class="ground"></div>
  <div class="content">FF下看有漂亮的圆角</div>
</div>