I was reading Twitter and someone posted a tweet with a photo and that it was created in CSS. It turns out the post was a hoax, but I figured that you can actually create photos in CSS, using box-shadow hack (you create 1x1px div and each pixel is single box-shadow). I was using it few years ago to create pixel graphic editor demo. So I've created something quickly on CodePen that get all pixels and create one big box-shadow. When I opened Google Chrome Dev Tools to copy the code it frozen because it was few MB of box shadow data. I was able to copy the text eventually and create HTML file. Later I've added a way to download a HTML file with your image on CodePen.

Here is the demo: https://jcu.bi/css-image