#iwm_map_canvas {
 width:100%;
 display: inline-block;
 position: relative;
 list-style: none;
}
#iwm_map_canvas:after {
    padding-top: 65%; 
    display: block;
    content: '';
}
#iwm_map_canvas div[id*='map_canvas_']  {
    position: absolute;
    top: 0; bottom: 0; right: 0; left: 0; 
}