Line break in Brine Collection Navigation Menu

Site URL: http://www.houseofgrey.co.uk

Hello,

I was wondering if there was a way of adding a line break to the Collection Nav item in Brine (this is the large overlay/rollover navigation on the landing page of Brine). I can isolate different menu items and alter their styling but can't find a successful way of forcing an element to stay on it's own line. For instance on the current live site, if 'Store' Could always be on its own line underneath the rest of the navigation.

I have a few janky workarounds like restricting the resizing of the text and the size of the container to pixels so it's not as responsive. I'll then have to resize the mobile menu since it will be huge... But, ideally I would just be able to force line breaks after certain links! 

Site is live: https://www.houseofgrey.co.uk

Thank you!

Brittany