Is it possible to set a minimum width of a Div using a percentage as width?

I currently have a div element that resizes to follow the window size, however I want it to stop resizing itself any smaller, using purely CSS. Is this possible, or should I use jQUERY?

div {width: 100%}

Basically what I have is the above, what I want to know is how do you set a minimum value in pixels? Like the below example:

div {min-width: 600px}

This doesn't appear to work as expected.