The daphne restaurant is centered on the page, so with resizing, it stays centered.
To emulate this, on your main div, in the CSS code add
and on your second div, in the CSS code add:
Is that what you were looking for? You can't really rewrite the CSS code based on how large someone's screen is.
Also, have a look at the following code. I've removed the parts you don't need, and changed the class/id stuff. It may help:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<div id="main">Content for id "main" Goes Here
Content for class "second" Goes Here