.translucent{    background:#000;    opacity: 0.5;    filter: progid:DXImageTransform.Microsoft.alpha(opacity=50);}

.bg-translucent{    background:rgba(0,0,0,0.5);/*前三个参数为rgb颜色，第四个参数为透明度*/    filter:progid:DXImageTransform.Microsoft.gradient(startcolorstr=#7F000000,endcolorstr=#7F000000);/*#7F000000的前两位为16进制透明度，后六位为16进制颜色*/}