The status bar displays the Document window’s current dimensions (in pixels). To design a page that looks its best at a specific size, you can adjust the Document window to any of the predetermined sizes, edit those predetermined sizes, or create sizes.
Resize the Document window to a predetermined size
Select one of the sizes from the
Window Size pop‑up menu at the bottom of the Document window.

The window size shown reflects the inside dimensions of the browser window, without borders; the monitor size is listed in parentheses. For example, you would use the size “536 x 196 (640 x 480, Default)” if your visitors are likely to be using Microsoft Internet Explorer or Netscape Navigator in their default configurations on a 640 x 480 monitor.
For less precise resizing, use your operating system’s
standard methods of resizing windows, such as dragging the lower-right
corner of a window.
Change the values listed in the Window Size pop‑up menu
Add a new size to the Window Size pop‑up menu