Jeremy Keith gave a great talk at An Event Apart about design principles. In the talk, he shows how everything should start with goals, which then lead to principles that reflect those goals, and finally result in design patterns to implement them.
In the early days of CSS-based design, square corners were a hallmark of designs that focused on simplicity of code, rather than visual aesthetics. Rounded corners remained somewhat painful to use, however, until the emergence of support for creating them using the border-radius property of CSS3. Now it takes only a few lines of simple CSS code to have nicely rounded corners—as long as you can accept that many users will see square corners until they move on to more modern browsers.
A Book Apart, the young book-publishing arm of the organization behind A List Apart and An Event Apart, has just released CSS3 for Web Designers, by Dan Cederholm, as a guide to CSS3 from the "what's really useful right now" perspective. As with the company's first book, HTML5 for Web Designers, this orientation, combined with an expert author, takes a large, complex subject and reduces it to a small, readable book.
Video is becoming more and more popular as an element of web pages. With the fragmented technology standards, providing video that plays everywhere can be tricky. Fortunately, there's an assortment of solutions available that package up all the complexity and provide a single, integrate solution for video that just works.
HTML5 includes a handful of new structural elements that are designed to make markup more meaningful. You can use these elements today; they don't really do much, so browsers don't need to explicitly support them. And it takes only a little trickery to make them work even in IE.
At its purest, the HTML5 video tag is a very simple. To deliver video that plays in Firefox and Safari, however, requires two different video formats, and you still need Flash for IE. Here's the code to make it happen.
Video on the web is a mess. Web standards have never fully embraced video. Until HTML5, there was no video element, so the only way to play video was to depend on platform-specific software. HTML5 provides a video element, but you're going to need to provide video in multiple formats.