- Beginner: https://frontendmasters.com/courses/web-development-v3/
- Intermediate: https://frontendmasters.com/courses/fullstack-app-next-v3/
- Advanced: https://frontendmasters.com/courses/svelte-v2/ and https://frontendmasters.com/courses/sveltekit/
Honorable mentions:
- https://www.joyofreact.com/
- https://css-for-js.dev/
- https://www.learnui.design/ for getting started designing yourself.