Taxi is a small and snappy js library for adding slick PJAX navigation and beautiful transitions to your website.

Halfmoon is a front-end framework with a built-in dark mode and full customizability using CSS variables; great for building dashboards and tools.

As they did for JavaScript, Sacha Greif and Raphaël Benitte launch the state of CSS 2019 based on survey. Check this out on this beautiful and clean website.