Shift propositional navigation down

This seems to be a custom thing done on Tim and Stephen’s prototype to
re-align the proposition nav. Not sure if it’s better or worse.

app/assets/stylesheets/app.scss

@@ -24,6 +24,9 @@
         padding: 0 0 0 15px;
       }
     }
+    #proposition-menu {
+      margin-top: 9px;
+    }
   }
 
 }