I'm trying to create a flexible layout on a webpage.

I would like the content of the page to be centered when using high resolution displays, and stay centered when the window size is reduced, all the way down to a minimum width which is the content width.

An example of this is what you see on bbc.com

I've tried placing all the content in a div an setting L: 15%, W:70% but this does not achieve the results I want at all.

Some direct advice or links to resources where I can learn this would be greatly appreciated!