Should you use that cool new HTML or CSS feature and if so, are there any issues you should think of? These questions are answered on this very handy site (which could be made a bit more handy if a cache manifest was added). It reminds me of When Can I Use… with the difference that this site gives some valuable advice. Handy.
Islands of Thought in Macrotypography · ART=WORK
One of the weirdest leftovers from the IE6 era is the fact that we don't use sibling selectors and thus never bothered to use real typography on the web. We're waking up now and realize that all along we could have read all these articles (about how bad IE6 is, for example) in a much more pleasant way. Nathan C. Ford tells us some things about paragraph indentation and gives us a handy bookmarklet.
Bulletproof HTML5 <details> fallback using jQuery · Mathias Bynens
Almost two years ago Mathias Bynens wrote an article about the
details element, how you can detect if it is supported and how you can polyfill it. He's been updating the article ever since (like he does with all his articles), for which he's earned yet again some extra internet points.
Learn You a Flexbox for Great Good! | The Haystack.
In December Stephen Hay published an excellent article about Flexbox on the Fronteers blog, in Dutch. For those of you that don't speak that language he took the time to translate it to proper English. You're very lucky, it's a very good article.
What The Heck Is Responsive Web Design?
Here's a nice presentation about responsive design: what it is, what flavours we have, how it works and some nice examples and resources as a bonus. (I like the effects used in the slideshow too)
Perfection kills » Profiling CSS for fun and profit. Optimization notes.
If you've been playing with CSS3 you've probably noticed that pages can get a bit slower when you add radii on boxes with complex gradients and complex box-shadows, especially if it's a complicated page with lots of DOM nodes, and it's a page you want to use to explain how responsive design works. For these occasions there are some very handy new optimization tools in Opera and Webkit that let you debug CSS. Here's a very thorough writeup by Juriy Zaytsev about how these tools work.
What To Do When You Meet A Sighted Person « The Dutch Prutser's Blog
We've been studying accessibility for years now and we know how a lot about how deaf, spastic and especially blind people use their computers and get by in general. But what do you know about sighted people? Not much probably. Here's an excellent article that explains a lot about their behaviour.
Test on Real Mobile Devices without Breaking the Bank | Brad Frost Web
You should test your websites on real devices, not just emulators, and not just on your own iPhone or Android device, there's much more out there that people actually use. But what devices should you get? Here's a list of devices that Brad Frost thinks you should have. Here's the list of devices I think you should have and Stephen Hay told me his pragmatic list last weekend: for every project you do just buy the device your client uses.
Adventures In The Third Dimension: CSS 3D Transforms - Smashing Coding | Smashing Coding
We've been faking depth with images and simple shadows on the web for years but now in more and more browsers we can use 3D Transforms with CSS. Peter Gasston wrote an excellent article about it which you should read, a few months from now a majority of your visitors will be able to see these transforms. Here's an example of what can be done with CSS3 3D.
Choosing device sizes to support for your responsive designs | Matt Wilcox .net
Responsive design, it sounds like a good idea and all but how do you design a responsive website? That's a legitimate question if up until now you've been building fixed width layouts, like most of us. Matt Wilcox explains the fluid, small screen first approach which I think is a very good one.
What we still can’t do client-side | Lea Verou
A lot of work that was traditionally done on the server is now done on the client and if it isn't it will be soon. There are some exceptions though and Lea Verou explains them, thorough and well informed as always.
Hurl is a nice little tool that shows you the response headers from a URL.
Lose the Wait: Page Weight and Transfer Weight | Zoompf
The bigger a site (in Kb) the slower it will be. That's easy and that's the basis behind the whole performance movement. Zoompf wrote a blog post about this simple principle with the promise that more will follow. I'm looking forward to reading them.
[open tabs] some reading I did lately and you can now, too | Christian Heilmann
Do you want more to read? Here's a nice collection of links, with comments, by Christian Heilmann.