Flash of unstyled content

Web pages often include style references to media other than the browser screen, such as CSS rules for printers and mobile devices.

Online advertisements and other inserted offsite content, like videos and search engines, often dictate their own style rules within their code block.

With the advent of JavaScript libraries such as jQuery which can be employed to further define and apply the styling of a web page, flashes of unstyled content have also become more prominent.

To emulate a flash of unstyled content, developers can use browser add-ons that are capable of disabling a web page's CSS on the fly.

While, by 2016, several different techniques had been developed to avoid undesired display behaviours,[2] a change in rendering behaviour in Google Chrome version 50, whereby stylesheets injected by JavaScript are prevented from blocking page loading, as required by the HTML5 specification, brought the situation to website creators' attentions again, particularly affecting users of Typekit, a web typography product from Adobe Systems.