It is not a standard but still tagged as a key approach for Responsive Web Design. This … Viewport size refers to the visible area available to a webpage inside a browser or application, minus that application's interface (such as URL bar, dev tools, operating system, etc. Elle est censée faire la même chose que la balise meta viewport mais en CSS. Comparison Table of Resolution, Pixel Ratio, Device Width and CSS media queries for iPhones. 2: you want width and height to both stay 100%, and you want the resulting change in aspect ratio to have the effect of a stretched-out image.