In this version of the Float 1 example I have taken the three sections from example Float 1b (the header topbox, the nav leftbox, and the section mainbox) and wrapped them in a new division (style name: #wrapper) that centers them in the window. Wrapper is 700 pixels wide and has its left and right margins set to auto, which causes it to be centered. It also has a background color that you can see it showing in the gaps between the three boxes it contains).
If I wanted this layout to butt right up against the top of the browser window, I would set the body margins to zero (which I have not done here) and set the top margin of the wrapper to zero (which is done in its style). As is, the default margins of the body are putting a little space between this layout and the top of the window.
This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page.
This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page. Pardon me while I repeat myself over and over and over again. This is the content for the main content area of the page.