Deliver non-mobile version of dashboard

I have a dashboard that fits perfectly on a 8" wall panel screen if rendered as regular desktop content. So using Chrome on that tablet and switching mode to “Desktop” renders it exactly right. Being detected as a mobile client, it will render about 10% too large and no longer fitting as perfectly as intended. I tried to change the user agent of the kiosk browser to the same being used by Chrome/Desktop, however it’s still rendered “mobile sized”, i.e. slightly too large.
How is responsiveness in HA implemented? Shouldn’t a desktop UA be sufficient to get the desktop rendering? Or is there any other “hack” i could try to have it rendered as being displayed by desktop, or prevent responsiveness altogether for such a dedicated “static” dashboard that is exactly made to fit for one specific device?
The strange thing about that: It fits totally fine on a Nexus 7 tablet (and is rendered as desktop size there), but not on a same size Lenovo M8 tablet, which insists on being a mobile browser…