ios - Trouble with layout on various screen sizes -

my screen layout has elements placed correctly

but when switch screen, eg. iphone 7 plus

or se

things change. i've set constrains, height , witdh when suppose should, apparently not want cooperate me. please tell me constrains , heights, widths should set.

add below constraint

1. for red , green view need give equal width constraint.
2. for blue view @ center need give center horizontally constraint.
3. for bar @ bottom need give bottom distance red/green top constraint.