Tailwind CSS is a popular CSS framework and enables styling and layouting without ever leaving the HTML-file. It uses CSS utility classes and in the ens a minified CSS file with only the parts used in included.
Play CDN for development
Use the CDN files/connection when developing, it is included with a simple one-liner.
<script src="https://cdn.tailwindcss.com"></script>
More information from Tailwind: https://tailwindcss.com/docs/installation/play-cdn
Creating output.css for production
When done the theme needs to be exported to generate the CSS-file.
Here are a guide for installation of Tailwind: