A method and system for selectively fully displaying additional content in a browser window, without requiring scrolling in more than one direction, based on an available display area. For example, additional advertising content is thus selectively displayed in an otherwise unused area of the browsing window to the right of a primary content of a Web page. The size of the available display area is automatically detected, and a determination is automatically made as to whether the additional content and primary content can both be fully displayed in the available display area under the scrolling constraint. If so, both the additional content and the primary content are displayed. Otherwise, only the primary content is displayed. The additional content is downloaded only when it can thus be included within the display area. If the browser window is resized so that the additional content no longer fits without scrolling in more than one direction, the additional content is removed from the display, but is preferably retained in local storage for redisplay if the available display area is subsequently increased sufficiently. The type (and version) of browser program used is detected so that the appropriate instructions will be provided to the client device to selectively display additional content in this manner. For smaller client device displays, such as on those on pocket PCs, the content provided by a server is selectively determined in a prioritized manner, as a function of the available display area.