How do I get my site to automatically fill a mobile screen?

Hi guys

I wonder if someone might be able to point me in the right direction.

How do I make my website automatically fit a mobile device?

I don’t want to use WP touch or such like, as I want the original website to look exactly as it does on a desktop. At the moment on an iphone, you only see the top left of the site, and you have to manually resize yourself by pinching the screen for it to fit the screen.

Does anyone know what code I need to add to make it do this? Everything I’ve researched on the net talks about detecting a mobile phone and then redirecting it to a mobile site etc. I however want to stay with the same site and just have the site fill the screen?

Rob