Responsive Navigation of Menu Items in Navigation

**Changes**
* Moved menu-items/navigation-links to left-aligned by default (we can make this only for mobile phones if required)
* Navigation-links disappear and Menu link appears for screen whose view-port is less than 600px
** On hover over Menu, the navigation links appears with sea-blue background

**Note:** The above Responsive Menu design is something I've seen and is fairly common in many sites these days. We can further customise it to our needs as required, based on feedback. I'd definitely appreciate a feedback on this .