Merge branch 'fix_responsive_layout_bug' into 'master'

Fix responsive bug top navigation

Hi,

I have found and fixed a minor layout bug (responsive)

This is the situation before the fix:
![before](/uploads/55bf61a64fb49a763c5f8381bf46d390/before.png)

And this is the situation after the fix:
![after](/uploads/33ba091156d404e52c41f134121c59f0/after.png)

See merge request !3190

app/assets/stylesheets/framework/nav.scss

@@ -63,7 +63,7 @@
     border-bottom: none;
 
     /* Small devices (phones, tablets, 768px and lower) */
-    @media (max-width: $screen-sm-min) {
+    @media (max-width: $screen-sm-max) {
       width: 100%;
     }
   }