Fix styling issues with tabs manager (#84)

less/documentDB.less

@@ -2351,6 +2351,7 @@ a:link {
 
 .tabsContainer {
     height: 100%;
+    width: 100%;
     overflow: hidden;
 }
 

src/explorer.html

@@ -193,7 +193,11 @@
               <div class="connectExplorer" data-bind="react: splashScreenAdapter"></div>
             </form>
           </div>
-          <tabs-manager class="tabsContainer" params="{data: tabsManager}"></tabs-manager>
+          <tabs-manager
+            class="tabsContainer"
+            params="{data: tabsManager}"
+            data-bind="visible: tabsManager.openedTabs().length > 0"
+          ></tabs-manager>
         </div>
         <!-- Collections Tree and Tabs - End -->
         <div