Let's see whether the image set is working. This would be tough without testing it on a retina display, which we're not doing. But let's see whether we can do some rough testing. Chrome has a nice feature where, if we inspect an image, we can see its src attribute and the srcset attribute. Check out the following code:
Here, if we hover the mouse over the path to each image, you can see that a popup appears over the image that's being served. But when we hover over jaws@2x, no popup appears because that image is not being served:
This makes sense as I'm not on a retina display, so it's using a non-retina image.
Let's ...