css 页面布局，自适应高度，居中，背景半透明

        body.bg-1 {

background-image: url(../images/backgrounds-1.jpg);

background-repeat: repeat, no-repeat;

background-position: left top;

background-size: auto, cover;

}

.login_main {

display: block;

text-align: center;

width:460px;

color: white;

position:absolute;

top:0px;bottom:0px;

left:50%;

margin-left:-230px;

}

/*背景半透明*/

.tm_png {

   

    background-color:transparent ;  

     background-image:url(../images/transparent.png) ;

/*_filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled=true, sizingMethod=scale, src="../images/transparent.png");*/

}