Birds are not narrow Animals - Mobiles are not narrow Desktops

Continuing through Vayikra; the weekly Torah reading:

There are 3 categories of sacrifices: Animals, Birds and Flour - each with its own method for sacrificing. 

E.g.: An animal is slaughtered the same way it's slaughtered for your kosher butcher, whereas a bird being sacrificed is slaughtered in a way that would make it unkosher for regular consumption. A flour offering is not slaughtered - that step is skipped.

When preparing a Technical Spec, one cannot simply treat the Mobile Phones as a narrow-screen desktop. That creates ridiculous and cumbersome interfaces.

A mobile User Interface must be designed specifically for a mobile device.

I recently used an interface that worked very nicely on a desktop - with the top left-hand side being your profile and dashboard - very convenient. But on a mobile the top of the screen was always your profile - and you had to scroll down to get any work done. 

That's what happens when you treat a mobile device as a narrow desktop.

And then you have the tablets - they cannot be ignored.

On a practical note, use a service like BrowserStack to see how your product looks on various devices and various browsers on those devices.