In general, the subject matter described in this specification can be embodied in methods, systems, and program products. A computing system presents graphical content on a display device. The computing system determines a change in distance between a user of the computing system and a camera by tracking a visible physical feature of the user through a series of images that are captured by the camera. The computing system determines that the user has physically contacted a user input device. The computing system modifies the graphical content to change (a) a level of detail of the graphical content based on the determined change in distance between the user and the camera, and (b) boundaries of a displayed region of the graphical content based on the determined physical contact with the user input device. The computing system presents the modified graphical content for display by the display device.