Viewport

A viewport is the visible area of a web page or application on a user's screen at any given moment. On a desktop computer, the viewport corresponds to the browser window minus toolbars, scrollbars, and browser chrome. On tablets and smartphones, the viewport is the full screen area the browser can use. The viewport determines how content is scaled, laid out, and presented to the reader. In HTML, the `<meta name="viewport">` tag tells the browser how to control the page's dimensions and scaling, which is the foundation of [responsive design](/glossary/responsive-design).

Content that ignores viewport differences delivers a poor reading experience on certain devices. Text may be illegibly small on phones, buttons may be impossible to tap, or horizontal scrolling may be required to see the full page. Since mobile devices now account for the majority of web traffic, publications that fail to adapt to different viewport sizes lose readers and appear unprofessional. Search engines also factor mobile-friendliness into rankings, so proper viewport handling affects both user experience and discoverability.

FlipLink publications are fully responsive and adapt automatically to any viewport size. The flipbook viewer detects the available viewport dimensions and adjusts page rendering, control placement, and zoom levels accordingly. On wide desktop viewports, publications display in a two-page [spread](/glossary/page-spread). On narrow mobile viewports, they switch to a single-page view with touch-friendly navigation. The [page experience](/features/page-experience-and-layout) settings let publishers choose between different layout modes, and FlipLink handles the viewport calculations to keep content legible and well-proportioned. When you embed a flipbook using the [responsive embed](/features/sharing-and-distribution) code, it automatically fills its container and responds to viewport changes — including device rotation — without any extra configuration.