https://codepen.io/anon/pen/xmJggB
I have this simple codepen, which has an image tag with a srcset of two images, one at 800px and 1000px wide.
Starting at a 401px wide screen, I would expect to see the 1000px wide image, (I'm on 2x retina, if you're not then at the 801px breakpoint.)
Instead it comes in at 448px?
Code:
<img srcset="https://via.placeholder.com/800 800w, https://via.placeholder.com/1000 1000w" sizes="100vw" />