Extended the current error message and suggestion message to include the...

Extended the current error message and suggestion message to include the possibility of a permissions issue, also made the error page responsive whilst I was at it

Updated CHANGELOG

Changed message to "You aren't where you think you are"

Changed sub-text

CHANGELOG

@@ -148,6 +148,7 @@ v 8.8.4
   - Fix LDAP-based login for users with 2FA enabled. !4493
   - Added descriptions to notification settings dropdown
   - Due date can be removed from milestones
+  - 404 page now shows the message "You aren't where you think you are." !4174
 v 8.8.3
   - Fix 404 page when viewing TODOs that contain milestones or labels in different projects. !4312

public/404.html

@@ -7,9 +7,9 @@
         color: #666;
         text-align: center;
         font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
-        margin: 0;
-        width: 800px;
-        margin: auto;
+        max-width: 800px;
+        width: 90%;
+        margin: 0 auto;
         font-size: 14px;
       }
@@ -39,6 +39,12 @@
         border-top: 1px solid #EEE;
         border-bottom: 1px solid white;
       }
+
+      img {
+          margin: 0 auto;
+          max-width: 210px;
+          width: 100%;
+      }
   </style>
 </head>
@@ -47,9 +53,11 @@
     <img src="data:image/svg+xml;base64,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" /><br />
     404
   </h1>
-  <h3>The page you're looking for could not be found.</h3>
+  <h3>
+    You aren’t where you think you are.
+  </h3>
   <hr/>
-  <p>Make sure the address is correct and that the page hasn't moved.</p>
+  <p>We are really sorry but the page your requested cannot be found.</p>
   <p>Please contact your GitLab administrator if you think this is a mistake.</p>
 </body>
 </html>