Div background height 100% (cover)

How can i set to a div a background image with a full height (as a cover)?

 .index-image-content{
 background: ##00aa77;
 background-image: url("../images/zenbg-1.png"), url("../images/zenbg-2.png");
 background-repeat: repeat-x, repeat;
 width:100%;
 height:auto;
 padding-top:20px;
 padding-bottom: 20px;
 color:#fff;

}

Thanks in advance !!