.blackbox{
position:fixed;
left:0;
top:0;
width:100%;
height:100%;
background-color:black;
opacity:0.3;
filter:progid:DXImageTransform.Microsoft.Alpha(opacity=30);//兼容IE
display:none;
z-index:8;
}
.signwin{
width:450px;
height:400px;
position:fixed;
left:50%;
top:40%;
margin-left:-225px;
margin-top:-200px;
background-color:none;
overflow:hidden;
border-radius:2px;
z-index:10;
border:none;
display:none;
}
