Just came on here to give @adamwathan some praise for one hell of a framework that I was naive enough not to use until now.
TailwindCSS + TailwindUI (free components) have literally 10x'd my frontend work productivity.
Built the landing page in lightning speed.
Plus, if you want to use TailwindUI with React, I'd recommend this chrome extension to convert the HTML to JSX.
I could not recommend Tailwind enough. Stop using vanilla HTML + CSS.