That was gemini-cli, I could see some mistakes on trial run so created a GEMINI.md with system prompt and project description (about 50 lines) which clarified some tricky source layout situations
Second run it was fine, ran for about an hour or so -- I had attempted to do it manually a while back but it started to look like it would take a week or two
EDIT: I haven't used Tailwind much but would something like this do what you're saying, or not really? https://www.loopple.com/tools/css-to-tailwind-converter
But this particular project is not like a standard site and the CSS is in small fragments across 100s files and uses constants for some things like color values in places too
In that Loopple example you can see the conversion uses the Tailwind arbitrary value notation, the -[], so background-color:#afa8af gets converted to bg-[#afa8af], but I wanted nearest pure tailwind class bg-zinc-400, the agent seems to work out color distance fine so does all that in one-shot too