GeotiefExplore/src/js/controls/MobileDialog.css

 .popup_close {
     background: url('data:image/png;base64,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')/*icons/close.png*/
     no-repeat;
 }

 /* anything but phone */

 @media all and (min-width: 768px) {
     .touch .popup_close {
         width: 20px;
         height: 20px;
         /*margin: 5px;*/
         background-size: 20px 20px;
         float: right;
         cursor: pointer;
         z-index: 800;
     }
     .touch .fm_overlay {
         top: 10em;
         left: 30%;
         max-width: 480px;
         min-width: 300px;
         /*max-height: 90%;*/
         max-height: 500px;
         overflow: auto;
     }
     .touch .popupcontent {
         width: 100%;
     }
 }

 /* only phone - bigger buttons */

 @media all and (max-width: 767px) {
     .touch .popup_close {
         background: url('data:image/png;base64,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')/*mobile_icons/close.png*/
         no-repeat;
         width: 25px;
         height: 25px;
         background-size: 25px 25px;
         float: right;
         cursor: pointer;
         z-index: 800;
     }
     .touch .fm_overlay {
         bottom: 4em;
         left: 20px;
         right: 20px;
         max-height: 70%;
         overflow-y: auto;
     }
     /*.touch .fm_basemap_list{  max-height: 80%; overflow-y: auto;}*/
 }

 .popup .fm_overlay {
     position: fixed;
     width: 300px;
     left: 50%;
     margin-left: -150px;
     top: 50%;
     margin-top: -150px;
     /* display: none; */
     z-index: 9999;
     padding: 10px;
     background-color: #ffffff;
     border: solid gray;
     border-width: 1px 2px 2px;
     border-radius: 3px;
 }

 .touch .popup .fm_overlay {
     /* display: none; */
     position: absolute;
     background-color: white;
     z-index: 9999;
     padding: 10px;
     border-radius: 1px;
     box-shadow: 0 0 0 10px rgba(34, 34, 34, .6);
 }

 .popup .fm_overlay.show {
     opacity: 1;
     transition: opacity 1000ms;
 }

 .popup .fm_overlay.hide {
     opacity: 0;
     transition: opacity 1000ms;
 }

 .popupbar {
     background: dimgray;
     color: white;
     padding-left: 4px;
     height: 20px;
 }

 .touch .popupbar {
     background: dimgray;
     color: white;
     padding-left: 4px;
     height: 25px;
 }

 .touch .popup_close {
     float: right;
     cursor: pointer;
     z-index: 800;
 }

 .popup_close {
     color: rgb(220, 220, 220);   
     border: 1px solid darkgray;
     border-radius: 4px;
     font-size: 16px;
     font-weight: bold;
     width: 16px;
     height: 16px;
     text-align: center;
     float: right;
     cursor: pointer;
     background-size: 16px 16px;
 }

 .fm_overlay {
     background-color: white;
     padding: 2px 5px 2px;
     max-height: 500px;
     overflow: auto;
     font-size: 14px;
 }

 .pageinfo {
     font-size: small;
 }

 .pageinfo h1 {
     background-color: gray;
     color: white;
     font-size: small;
     font-weight: normal;
     margin-top: 5px;
     margin-bottom: 3px;
     padding: 1px;
     padding-left: 6px;
 }

 .license {
     font-size: xx-small;
 }

 .star {
     padding: 5px;
     text-align: left;
 }