Hi @clefler,
Thanks for reaching out.
It looks like it doesn’t load all the resources when that tools check our sales page. You’ll see in your screenshot that the styling are off which I can confirm when I viewed it too. Our sales page also uses an old version of the theme, there is nothing to change or redesign at this moment. Our demos are also unreachable from that tool too, I suggest testing an actual website, like your website.
And I actually tested the site in your account, and it’s mobile friendly 
Plus, it’s also how you built your content. Like padding, spacing, sizes, and layout. The theme is just a framework, the final rendering depends on the user.
Cheers!