To whitelist/safelist you can make use of safelist in the configuration "tailwind.config.js". Now when you compile your tailwind but you didn't use the classes it will still present in the compiled CSS file as it's within the "safelist".
module.exports = {
content: [
'./pages/**/*.{html,js}'
'./components/**/*.{html,js}',
],
safelist: [
'bg-red-500',
'text-3xl',
'lg:text-4xl',
]
// ...
}
