Horizontal scrolling isn't that bad on mobile devices. I wouldn't want to scroll one of these on desktop but it's so simple to just, flick through it with my finger on a phone.
Just put it behind a media query when your desktop-sized nav bar gets too big?
It can be OK in some cases, but it can be hard to discover unless it's very obvious. Thanks to Apple hiding scroll bars, if the elements in a horizontal scroll happen to line up with the edge of the screen it can be impossible to tell that horizontal scrolling is even an option unless you trigger it accidentally.
Edit: Oh yeah, and horizontal scrolling interacts unpredicatably with horizontal gestures on mobile. E.g. forward/back in iOS Safari.
Once I got confused on Google maps android, because I thought they had removed the "Share" button. It was a sausage menu, but the size of the buttons were such that the rest of the buttons were perfectly hidden (you could not see the rest of a half button) and of course there was no visible horizontal scrollbar.
> Horizontal scrolling isn't that bad on mobile devices
I disagree, it’s not easily discoverable and I have yet to see a single website that implements it well in any context. I alway find elements scrolling multiple directions at once or end up scrolling down the page instead.
It's not bad UX per se (I love it for certain mobile uses), but it's bad to make an assumption that horizontal scrolling is always available.
Similarly, it's bad to assume that everyone is always using a keyboard and mouse (a frustration I encounter in Desktop environment communities (e.g. Gnome / Linux) in gesturing that some use tablet PCs).
Just put it behind a media query when your desktop-sized nav bar gets too big?