Minimal CSS-only blurry image placeholders

I’m not the world’s biggest fan of LQIP’s (low quality image placeholders) generally (doing nothing other than handling aspect ratio is… fine), but I really like how much creativity it inspires. I’ve seen a ton of different approaches to it over the years, that all use different technology and all have different advantages and disadvantages. Lean Rada has another interesting take with Minimal CSS-only blurry image placeholders where a single custom property is the seed for massively different CSS backgrounds generated from overlapping radial gradients with oklab colors.