Improve mobile experience

the generate invite box now wraps into 1 column automatically.
the invite code is ellipsized on small displays.
the dropdown button has a large tappable area, and is aligned correctly.

data/templates/admin.html

@@ -117,6 +117,13 @@
              -o-transition: all 150ms cubic-bezier(0.770, 0.000, 0.175, 1.000);
                 transition: all 150ms cubic-bezier(0.770, 0.000, 0.175, 1.000); /* easeInOutQuart */
             }
+
+            .invite-link {
+                text-overflow: ellipsis;
+                overflow: hidden;
+                white-space: nowrap;
+                width: auto;
+            }
         </style>
         <title>Admin</title>
     </head>
@@ -280,7 +287,7 @@
                                         </select>
                                     </div>
                                 </div>
-                                <div class="col">
+                                <div class="col-md-auto">
                                     <div class="form-group">
                                         <label for="multiUseCount">
                                             Multiple uses