Google is going to start letting mobile searchers know when results include pages that may not work on their devices. On a device that doesn’t support Flash, for example (which includes iOS and Android versions 4.1 and higher), Google will include a message with the result that says, “Uses Flash. May not work on your device.”

“A common annoyance for web users is when websites require browser technologies that are not supported by their device,” write Google’s Keita Oda and Pierre Far. “When users access such pages, they may see nothing but a blank space or miss out a large portion of the page’s contents.”

Here’s what one of the results may look like:

“Fortunately, making websites that work on all modern devices is not that hard: websites can use HTML5 since it is universally supported, sometimes exclusively, by all devices,” the Googlers say. “To help webmasters build websites that work on all types of devices regardless of the type of content they wish to serve, we recently announced two resources: Web Fundamentals (a curated source for modern best practices); and Web Starter Kit (a starter framework supporting the Web Fundamentals best practices out of the box).”

You can find Web Fundamentals here. On the site it’s described as a comprehensive resource for multi-device web development. It includes sections on multi-device tools, multi-device layous, forms and user input, images/audio/video, optimising performance, and device access.

Web Starter Kit is here. From the site, you can download the beta kit, which includes a responsive boilerplate, a style guide, cross-device sync, live browser reloading, performance optimization, a built-in HTTP server, PageSpeed Insights reporting, and Sass support.

Google also notes that you should not block crawling of any Googlebot of CSS, JavaScript or images with robots.txt or otherwise.

Image via Google