Radio Buttons & Stretching 100% on screen.

Radio Buttons & Stretching 100% on screen.

I am trying to develop an app on the iPhone.  However due to the different sizes of the screens one of the problems I have is with radio buttons.

I have a set that needs to stretch across the screen but I am completely stumped by it.

I have created a fiddle,  http://jsfiddle.net/83LpjLe0/,

Any help would be really appreciated.

Thanks.