Does anyone know what was used to render these code blocks in the article? The mouseover tooltip is extremely cool. I've never seen anything like it before. ED

Does anyone know what was used to render these code blocks in the article? The mouseover tooltip is extremely cool. I've never seen anything like it before. EDIT: I dug through the codebase and determined that it's using Shiki and TwoSlash for the syntax highlighting and tooltips.