Level 88
You need to call purgeCss after your sass, and specify the options for postCss.
For example
mix.sass('resources/sass/app.scss', 'public/css')
.options({
processCssUrls: false,
postCss: [ tailwindcss('./tailwind.config.js') ]
})
.purgeCss({
enabled: mix.inProduction(),
folders: ['src', 'templates'],
extensions: ['html', 'js', 'php', 'vue'],
});