So we cracked it. My colleague changed some settings at Amazon, I don't know what, and I added crossorigin="anonymous" to every <img> . I'll be completely honest and say I'd never heard of that attribute before this.

I worked at this today with a couple of colleagues and we think we've narrowed it down to cache busting query parameters on image URLs.

One of the sites I used a lot and see recommended a lot is WebAIM http://webaim.org

One of my favourites is :invalid . You can tie it in with ARIA for a really nice UX on frontend validation. So for example input:not([type=checkbox]):valid:not(:focus)+label::after { content: " ✓" } (It requires the input to come before the label which is fine for a11y and easy fixed visually with flexbox or positioning.

That is the best tutorial on perspective I have ever seen, thanks for sharing :)

First of all your advocacy for CSS grid layout and the resources you have provided on it are amazing, thank you! My question is what future do you see for front end developers who are great at semantic and accessible HTML, and great at CSS knowledge and architecture, but will never be JS engineers?