GUI -- Added dark theming for the topology view.

Change-Id: I13c7bbbff65007fed162a4ea80dbf6042ff04c07
diff --git a/web/gui/src/main/webapp/app/fw/mast/mast.css b/web/gui/src/main/webapp/app/fw/mast/mast.css
index 0722f6d..33c6959 100644
--- a/web/gui/src/main/webapp/app/fw/mast/mast.css
+++ b/web/gui/src/main/webapp/app/fw/mast/mast.css
@@ -32,7 +32,7 @@
 }
 .dark #mast {
     background-color: #444;
-    box-shadow: 0 2px 8px #777;
+    box-shadow: 0 2px 8px #222;
 }
 
 #mast img.logo {