Simon Willison’s Weblog

Side-channel attacking browsers through CSS3 features. Really clever attack. Sites like Facebook offer iframe widgets which show the user’s name, but due to the cross-origin resource policy cannot be introspected by the site on which they are embedded. By using CSS3 blend modes it’s possible to construct a timing attack where a stack of divs layered over the top of the iframe can be used to derive the embedded content, by taking advantage of blend modes that take different amounts of time depending on the colour of the underlying pixel. Patched in Firefox 60 and Chrome 63. # 1st June 2018, 2:54 pm

Scribd in HTML5. Outstanding piece of engineering work from Scribd—they can now render documents using HTML, webfonts and a ton of CSS absolute positioning (using ems rather than pixels) instead of Flash. Nothing to do with HTML5 of course, which is rapidly replacing Ajax as the most mis-applied terminology on the Web. That nit-pick feels pretty insignificant compared to their overall achievement though—being able to convert any formatted document (.doc, pdf etc) in to HTML and CSS that displays correctly is a real leap forward. # 7th May 2010, 12:09 pm

Pure CSS3 Spiderman Cartoon w/ jQuery and HTML5. Great demo, though calling -webkit-animation HTML5 (or even CSS3) is a bit of a stretch... # 4th May 2010, 7:27 pm

Internet Explorer Platform Preview Guide for Developers (via) Lots of SVG and CSS3 stuff, no mention of canvas here either though. # 16th March 2010, 6:36 pm

CSS 3: Progress! Alex Russell on the new exciting stuff going in to CSS 3 based on real-world implementations in the modern set of browsers. Of particular interest is the new Flexible Box specification, which specifies new layout primitives hbox and vbox (as seen in XUL) and is already supported by both WebKit and Gecko. # 22nd August 2009, 11:52 am

A brief introduction to Opacity and RGBA. The CSS opacity property is inherited by an element’s children; opacity set using the new rgba() declaration in CSS 3 differs in that it is not inherited. # 17th March 2008, 2 am

CSS3 and the death of Handheld Stylesheets. I hadn’t looked at CSS 3 media queries before (which let you apply different styles based on media features such as screen width, height and colour availability)—they seem like a much smarter solution that handheld stylesheets and also appear to be preferred by device vendors. # 16th November 2007, 9:53 am

lxml.cssselect (via) lxml includes an implementation of CSS 3 selectors, which compiles them to XPath expressions. Should be a useful tool for parsing Microformats from Python. # 24th September 2007, 11:57 pm

Opera 9.5 (Kestrel). The latest Opera alpha includes a bunch of CSS3 features (including an almost full implementation of CSS3 Selectors) as well as the ability to use SVG for scalable background images. # 4th September 2007, 10:49 am