image url in the asp.net custom server control

See more:

controls

ASP.NET4

Hi,
I created a new project for asp.net server control and also added internal.js,style.css and a background-image which is quoted in the style.css.

.location-clear {
    background: url("image/ui-icons_2e83ff_256x240.png") repeat scroll -98px -366px rgba(0, 0, 0, 0);
    display: none;
    height: 16px;
    position: absolute;
    width: 16px;
}

Because of the issue of image url,it dosen't display on the cilent side.I know the url of image like this:

/WebResource.axd?d=DHlEQqJ73pe7w6G7zgj4BSIjdH_IYR-zB3WSMZ236lT0QdbSWqzOsxPdeCUhWhtjDBq_DIBSgsXWN2vc_A48WxFsNBhVkLfXhGabkCYoP48lLC5Ob2oI6hGENOfbpyne0&t=635596203601401714

I think I'd better get this dynamic url and replace the static with it,but I'm not sure what to do.Will you please give some idea?

Thanks a lot.