#curtains {
                transition-property:background-position;
                transition-duration:2s;
                transition-timing-function:ease-out;
                border:1px solid blue;
                text-align:center;
                font-size:200%;
                font-weight:bold;
                color:black;
                width: 400px;
                height: 300px;
                margin:auto;
                background: url(../images/curtains-left.jpg) 0px 0px no-repeat, 
                url(../images/curtains-right.jpg) right top no-repeat, 
                url(../images/sunrise.jpg) left top repeat-x; 
            } 
#curtains:hover {
                            transition-property:background-position;
                            transition-duration:2s;
                            transition-timing-function:ease-out;
                            color:white;
                            background-position: -201px 0px, 450px 0px, left top;
                        }

http://coboldinosaur.com/pages/CSS_Background_Images.html

Each image is positioned, dimensioned, and repeated according to the comma separated values in the other background properties. The images in the list are layered front to back in the same order they are listed in the rule declaration. If a background color is specified it will be the bottom layer.

Curtain Effect Using Multiple Background Images

images, background, CSS3, html5

CSS