config_service: add link to go back to the front page

appengine/config_service/ui/src/config-ui/config-ui.html

 <!--
   Copyright 2017 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 -->
 
 <link rel="import" href="../../bower_components/polymer/polymer.html">
 <link rel="import" href="../../bower_components/paper-search/paper-search-bar.html">
 <link rel="import" href="../../bower_components/app-route/app-location.html">
 <link rel="import" href="../../bower_components/app-route/app-route.html">
@@ skipping 28 matching lines @@
         color: #232323;
       }
 
       .link {
         font-size: 75%;
         color: white;
         margin-right: 10px;
       }
 
       .title {
+        text-decoration: none;
         color: white;
-        font-size: 125%;
+        font-size: 115%;
       }
+
+      [main-title] {
+        pointer-events: auto;
+        margin-right: 100px;
+      }
+
     </style>
 
     <app-drawer-layout fullbleed force-narrow>
       <app-header-layout>
         <app-header reveals slot="header">
           <app-toolbar>
             <!--<image class="logo" src="/static/images/chromium.png"/>-->
-            <div class="title" main-title>
-              Configuration Service
+            <div main-title>
+              <a href="/#/" class="title">
+                Configuration Service
+              </a>
             </div>
 
             <a href="https://luci-config.appspot.com/_ah/api/explorer" 
                class="link" 
                target="_blank"> APIs explorer 
             </a>
 
             <template is="dom-if" if="[[client_id]]">
               <auth-signin
                   class="right"
@@ skipping 72 matching lines @@
           // If the path is blank, redirect to /
           if (!this.route.path) {
             this.set('route.path', '/');
           }
         });
       },
 
     });
   </script>
 </dom-module>