How do I Scale game to screen size using cocoonjs export

Hi everyone! I have a problem. When i export to ludei's cocoonjs with an portrait orientation option and "letterbox scale" in construct 2 and compile my app, it have very strange scale rate, not fullscreen and some objects can be visible untill they spawn. But if i export to an html 5 and run it browser with the same scale mode "Letterbox scale" it scales to resolution of my pc screen just fine. So is there any trick to solve this problem without remaking everything in game to the new resolution and using outer scale to export with coocoonjs?

Thanks for help!

My windows size in construct 2 is 400X500

Cocoonjs just doesn't support letterbox modes. That has been a long standing limitation and annoyance.

I tried to export with intel's crosswalk for android, but every time i try to do this i get an error "Build failed bla,bla,bla" check your assets.

if you tell us the Blah.blah,blah we might be able to help get you up and running