bars, and Teenage Mutant Ninja Turtles II: The Arcade Game and Vice: Project Doom for NES use it to scroll background layers at different rates. More advanced raster techniques can produce interesting effects. A system can achieve a very effective depth of field if layers with rasters are combined; Sonic the Hedgehog, Sonic The Hedgehog 2, ActRaiser, Lionheart, Kid Chaos and Street Fighter II used this effect well. If each scanline has its own layer, the Pole Position effect is produced, which creates a pseudo-3D road (or a pseudo-3D ball court as in NBA Jam) on a 2D system. If the display system supports rotation and scaling in addition to scrolling—an effect popularly known as Mode 7—changing the rotation and scaling factors can draw a projection of a plane (as in F-Zero and Super Mario Kart) or can warp the playfield to create an extra challenge factor. Another advanced technique is row/column scrolling, where rows/columns of tiles on a screen can be scrolled individually. This technique is implemented in the graphics chips of various Sega arcade system boards since the Sega Space Harrier and System 16, the Sega Mega Drive/Genesis console, and the Capcom CP System, Irem M-92 and Taito F3 System arcade game boards. Example In the following animation, three layers are moving leftward at different speeds. Their speeds decrease from front to back and correspond to increases in relative distance from the viewer. The ground layer is moving 8 times as fast as the vegetation layer. The vegetation layer is moving two times as fast as the cloud layer. Parallax scrolling in Web design One of the first implementations of parallax scrolling in the browser was created and shared in a blog post by web developer Glutnix in 2007, this included example code and a demo using JavaScript and CSS 2 that supported Internet Explorer 6 and other browsers of that era. However, it wasn't until 2011 and the introduction of HTML5 and CSS 3 coding that the technique became popular with Web designers. Advocates argue it is a simple way to embrace the fluidity of the Web. Proponents use parallax backgrounds as a tool to better engage users and improve the overall experience that a website provides. However, a Purdue University study, published in 2013, revealed the following findings: "... although parallax scrolling enhanced certain aspects of the user experience, it did not necessarily improve the overall