PUBLIC MARKS from decembre with tags example & firefox

element() brings CSS design to a new level, in an easily way. Few ideas that comes to my mind (some that I've already used since the last 4 years): - when you have to deal with duplicated content in advanced effects - live thumbnails of previous/next slides in a slideshow - live zoom over an image, for example in an e-commerce product page - animated background, using CSS Animations or by referencing a video, canvas or SVG - faking backdrop-filter or filter() - watermark with multiples backgrounds from Lea Verou idea - and anything you’re currently thinking of ;) Few things we can note: - prefixed for now in Firefox: -moz-element() - impact on rendering performance when using multiple reference. Not as bad as CSS filters, but still something you have to consider - there’s a CanIUse support page - Issue Chromium - Issue WebKit - No mention from IE Platform Status

To help illustrate how to develop extensions, we maintain a repository of simple example extensions at https://github.com/mdn/webextensions-examples. This article describes the WebExtension APIs used in that repository.

On Firefox Greasemonkey, you can do that with the stupefyingly brilliant (^_^) checkForBadJavascripts utility

A style I made for fun, to round the first tab top left corner, and new tab top right corner. A good demonstration of using child tokens