We recently reworked Firefox for Android‘s homescreen to look a little prettier on first-run by shipping “tile” icons and colors for the default sites. In Firefox 33, we’re allowing sites to designate their own tiles images by supporting  msApplication-Tile and Colors in Fennec. So, for example, you might start seeing tiles that look like:

appear as you browse. Sites can add these with just a little markup in the page:

As you can see above in the Boston Globe tile, sometimes we don’t have much to work with. Firefox for Android already supports the sizes attribute on favicon links, and our fabulous intern Chris Kitching improved things even more last year. In the absence of a tile, we’ll show a screenshot. If you’ve designated that Firefox shouldn’t cache the content of your site for security reasons, we’ll use the most appropriate size we can find and pull colors out of it for the background. But if sites can provide us with this information directly its 1.) must faster and 2.) gives much better results.

AFAIK, there is no standard spec for these types of meta tags, and none in the works either. Its a bit of the wild wild west right now. For instance, Apple supports apple-mobile-web-app-status-bar-style for designating the color of the status bar in certain situations, as well as a host of images for use in different situations.

Opera at one point supported using a minimized media query to designate a stylesheet for thumbnails (sadly they’ve removed all of those docs, so instead you just get a github link to an html file there). Gecko doesn’t have view-mode media query support currently, and not many sites have implemented it anyway, but it might in the future provide a standards based alternative. That said, there are enough useful reasons to know a “color” or a few different “logos” for an app or site, that it might be useful to come up with some standards based ways to list these things in pages.

http://digdug2k.wordpress.com/2014/07/30/better-tiles-in-fennec/