I've got tailwindcss ^2.2.19 when I setup my project. I notice that jit didn't work. The output app.css size is 4 MB. I had to add --jit to my watch command: npx: [ "tailwindcss", "--input=css/app.css", "--output=../priv/static/assets/app.css", "--postcss", "--watch", "--jit", cd: Path.expand("../assets", __DIR__) ],