First of: Pres F12 in your Darkorbit spacemap tab
You might have to press the small smartphone icon on the upper left to activate the device mode first.
This button
_______________________________________
Now you should see all of this
_______________________________________
You should now use the lower window, where you can choose between

and
Go to "Emulate"
_______________________________________
Now you're at Emulate->Device, where you can check "Emulate screen resolution". Check that and then you can change, how high and wide the resolution should be.
?. Profit