[html] Min width in window resizing

I have a webpage with a fluid layout with a 100% width.

When I resize browser window the elements in the page overlap.

I would create an effect similar to this website http://bologna.bakeca.it/ that when window is smaller than a fixed width stop resizing.

Well, you pretty much gave yourself the answer. In your CSS give the containing element a min-width. If you have to support IE6 you can use the min-width-trick:

#container {
    min-width:800px;
    width: auto !important;
    width:800px;
}

That will effectively give you 800px min-width in IE6 and any up-to-date browsers.