半透明在IE和火狐下的写法

filter:alpha(opacity=80);opacity:0.8;
filter:progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr=#99000000, endColorstr=#99000000);background:rgba(0,0,0,.6);
-ms-filter:"progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr='#66000000', endColorstr='#66000000')";
#filter:progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr='#66000000', endColorstr='#66000000');
background-color:rgba(0,0,0,0.4);

filter:alpha(opacity=80);opacity:0.8; filter:progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr=#99000000, endColorstr=#99000000);background:rgba(0,0,0,.6); -ms-filter:"progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr='#66000000', endColorstr='#66000000')"; #filter:progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr='#66000000', endColorstr='#66000000'); background-color:rgba(0,0,0,0.4);