ONOS-5622 fix the map Map selection dialog style problem

Change-Id: Iaafd49725dff74deade4dd7d28ee4e9b72604f27
diff --git a/web/gui/src/main/webapp/app/view/topo/topo.css b/web/gui/src/main/webapp/app/view/topo/topo.css
index 854c99b..eb86556 100644
--- a/web/gui/src/main/webapp/app/view/topo/topo.css
+++ b/web/gui/src/main/webapp/app/view/topo/topo.css
@@ -255,5 +255,5 @@
 }
 
 .map-list select {
-    font-size: 20px;
+    font-size: 16px;
 }