Been a while since I wrote this up but I still love that you can dynamically toggle a "sizes" attribute from say, 100vw to 200vw to cause the browser to select an contextually-appropriate, higher resolution source from its "srcset" list. It's such a cheap way to drive a "zoom" feature for product images, and it actually surprised me when it worked at the time. Responsive Image standards are good. https://www.filamentgroup.com/lab/sizes-swap/
