Amendment: Images:

[michaelspellacy]

We need to add two items in images section.

1. Guidelines for use of <picture> element (and srcset and sizes)
2. Accessibility reminder on adding null alts (alt="").

[michaelspellacy]

Okay, since I brought it up, I will propose what should be included in the document. Stay tuned.

[michaelspellacy]

Bumping this up.

[Brockenstein]

I always do picture with the img src as the deskop size and the picture srcset as the device size specific image using max-width. The reason being is because ie10 does not support picture and so it will render the img. You don't need to worry about mobile on ie10 because ie10 is not on mobile devices.

<picture>
    <source srcset="//via.placeholder.com/350x150?text=mobile+pic" media="(max-width: 600px)">
    <img src="//via.placeholder.com/1000x600?text=desktop+pic" alt="">
</picture>