I couldn't find a library for this functionality that didn't require
jQuery, and I don't want to be adding *more* jQuery requirements. So, I
decided to throw together my own!
The `<magic-magnifier>` component copies its contents into a "lens"
element, then uses basic JS to track mouse position, then uses CSS to
move the lens and its contents into a helpful position.
One thing I noticed here is that the zoom is a bit crunchy because
we're using PNG images, and it's hard to zoom in even further than we
already are. I might try switching this UI to use the SVG images by
default instead?
