Format not working when previewing layouts in web and ios

When i build the app i have assets width 320px and when I preview they extend outside of these limits. All the containers and text fields/buttons are within the confines of the 340 group but they still stretch.

Any ideas?

I cant get this fixed, please help. frustrating im sure its a silly detail but i cant find out why!

This is based on the component being responsive to screen size I believe. They way I solve for it is to make the list component itself (yellow box in your screenshot) full width, and then add padding from the edge to my components. It also helps to ensure that none of the interior pieces of the list get cut off from another component that may touch the list.