ul.TINYMCE_gallery {
    background-color:#CCC;
    border:1px solid #333;
    padding:10px;
    margin:0;
    list-style-type:none;
    background: #CCC url(../img/gallery.gif) no-repeat top right;

}

ul.TINYMCE_gallery li {
    margin-bottom:5px;
}
ul.TINYMCE_gallery li img {width:200px}