add missing css file for OL viewer

extra/lib/theme/default/style.mobile.css

@@ -0,0 +1,70 @@
+div.olControlZoom {
+    position: absolute;
+    top: 8px;
+    left: 8px;
+    background: rgba(255,255,255,0.4);
+    border-radius: 4px;
+    padding: 2px;
+}
+* {
+    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
+}
+div.olControlZoom a {
+    display: block;
+    margin: 1px;
+    padding: 0;
+    color: white;
+    font-size: 28px;
+    font-family: sans-serif;
+    font-weight: bold;
+    text-decoration: none;
+    text-align: center;
+    height: 32px;
+    width: 32px;
+    line-height: 28px;
+    text-shadow: 0 0 3px rgba(0,0,0,0.8);
+    background: #130085; /* fallback for IE - IE6 requires background shorthand*/
+    background: rgba(0, 60, 136, 0.5);
+    filter: alpha(opacity=80);
+}
+a.olControlZoomIn {
+    border-radius: 4px 4px 0 0;
+}
+a.olControlZoomOut {
+    border-radius: 0 0 4px 4px;
+}
+div.olControlZoom a:hover {
+    background: #130085; /* fallback for IE */
+    background: rgba(0, 60, 136, 0.7);
+    filter: alpha(opacity=100);
+}
+@media only screen and (max-width: 600px) {
+    div.olControlZoom a:hover {
+        background: rgba(0, 60, 136, 0.5);
+    }
+}
+div.olMapViewport {
+    -ms-touch-action: none;
+}
+.olLayerGrid .olTileImage {
+    -webkit-transition: opacity 0.2s linear;
+    -moz-transition: opacity 0.2s linear;
+    -o-transition: opacity 0.2s linear;
+    transition: opacity 0.2s linear;
+}
+/* Turn on GPU support where available */
+.olTileImage {
+    -webkit-transform: translateZ(0);
+    -moz-transform: translateZ(0);
+    -o-transform: translateZ(0);
+    -ms-transform: translateZ(0);
+    transform: translateZ(0);
+    -webkit-backface-visibility: hidden;
+    -moz-backface-visibility: hidden;
+    -ms-backface-visibility: hidden;
+    backface-visibility: hidden;
+    -webkit-perspective: 1000;
+    -moz-perspective: 1000;
+    -ms-perspective: 1000;
+    perspective: 1000;
+}