Most web sites are now viewed from devices such as smartphones or tablet. You need a layout which adapt nicely to any screen size. To be fully web responsive, to be adapted to all type of devices, a web site has to be designed for this. The layout must be thought from the beginning to smoothly fit all size and types. Also the Apple products and Android system may show conflicts in sliding and scrolling effects. This as to be corrected with Javascript. To check if a web site is web responsive reduce progressively your browser window horizontally. To see all size rendered in a single window, go to http://www.websitedimensions.com/sitegrid/index.php