I also considered calling this "Why zoom sucks on mobile", as that is the biggest issue with zooming & web development. To understand why I'll walk through the different ways zoom works on desktop and mobile.
I recently started experimenting with flexbox. On this blog. Without enough testing. Or at least, without the kind of testing I would do for a work project. It's a live experiment! Here are the bugs I ran into.
Lessons learned from a project by Hans Hillen and Jennifer Gauvreau, what should have worked that didn't! Lots of JAWs/IE bugs and how they got around them.
Denis Boudreau and Wayne Dick presented on why browser zoom sucks, firstly from the point of view of testing with WCAG, and then from a low-vision user's point of view.
Doug Schepers on data visualisation with Web technologies such as SVG, Canvas, ARIA, and the Web Audio API, so that you can make accessible information graphics.
A presentation on the parallels between responsive design and accessible design By George Zamfir.
Taking my arguments about pixels being relative another step, the CSS pixel sizes that device makers use actually tell us the distance away from your eye that they think you should hold a device. Applying a bit of maths lets us work out what that distance is.
I keep reading recommendations for using EMs or other typographical units for layout, which I still don't understand. At best it is an extra layer of abstraction, at worst it is misleading and likely to cause more issues than it solves. I will try to demonstrate why pixels are the best relative unit.
Layout methods in web design have gone through a transition in the last few years, unfortunately we're still using floats a lot, but flexible layouts have made a comeback in the form of responsive design - which is great. Recently though, I have been puzzled by people suggesting that we should use EMs for layout...
I've noticed a bug in Webkit browsers that impacts accessibility: Zooming in does not trigger media queries. Responsive design techniques can really help people who zoom in with their browser, but not in Chrome or Safari at the moment.