Vid 1936

Also, let's pick a direction (small -> large or large -> small) and stick with it, avoiding specifying min-width and max-width values. From the spec: 
> The user agent will choose the first source element for which the media query in the media attribute matches, and then choose an appropriate URL from its srcset attribute.
So if we decide to go "mobile first" and start with small screens, it would be something like: max-width:768px, max-width:1024px, etc.