Responsive Homepage with Dropdown Menus

I am practicing on making a full-page site and this site's navigation bar is a really good practice. I have enjoyed the challenge in this one. I have been enjoying on using SASS for writing CSS but there are times where I get confused if I put the selector in component partial or the desktop or mobile partial. I hope that the more I write SASS will help me sort this one better.

My biggest challenge for this was the dropdown menu, I have managed to make it work but I am not very confident about the Javascript.

Any feedback is welcome :)