This is a personal portfolio website made using Next.js. It uses Sanity.io as a headless CMS and the SendGrid API for contact form submissions. There is no reason you couldn't incorporate a CSS framework with a bit of work....
You can clone this project and edit the files in /src/, but you'll also need to update the sanity and sendgrid config in order for everything to work (including adding a .env file + keys in the root)!