Height equals width with pure CSS
"We define a pseudo element for our box and give it a margin-top of 100%. Since this 100% value relates to the element's width... you get it"
5 HTML5 and ARIA design patterns | Feature | .net magazine
"This article takes five HTML5 and ARIA design patterns and explains why they make good design choices"
DiagnostiCSS // Visually detect any potentially invalid or inaccessible HTML markup
"Visually detect any potentially invalid or inaccessible HTML markup*"
CyberCrab - Responsive design testing tool - Viewport Resizer - Device simulation tool - Resolution Tester - Responsive Screen Tester - Responsive Screen Tester - Screen Check - Resolution Tester
"Check your website at different screen resolutions"
13 Stats to Convince Your Boss to Invest in Mobile in 2013 | Mobify
"To help you pitch your boss and frame the situation from their perspective, we've prepared a collection of the most exciting numbers around the mobile web. It will help you get the attention of any skeptic, be it your manager, your client, or your mom."
Five reasons why you should quote attribute values in HTML5 | Web Directions
"So, we need to quote attributes values when they include spaces. But that's not all. Unquoted attribute values must also not contain any of these characters"
CSS viewport units: vw, vh, vmin and vmax - Dev.Opera
"One type of units that has not been so widely discussed is viewport units, for sizing things relative to the viewport size, a brilliant proposition for responsive design. They are currently supported by a reasonable variety of browsers (Opera 15, Firefox, Chrome, Blackberry 10, IE10, iOS), and allow for a lot of interesting new possibilities."