The Browser Viewport
The browser viewport is the window in the browser through which the document content is viewed. This is a fairly simple concept, but, again, it's a distinct one from containing blocks.In positioning, in some cases, element boxes are positioned in relation to the viewport and not normal flow or containing blocks. So understanding the viewport is important (see Figure 12-4).
Figure 12-4. The Firefox browser with sidebar, menus, and status barthe viewport is only the window through which you're seeing the document.
[View full size image]
