Ask HN: How do I master Front End development?

Interviewed for a pure Front End Dev role today. Realized I have a long way to go. Just wanted to find some inspiration in this community and understand how did you get into Front End Development, and followed through your ambitions? From an .NET Web Dev background, focusing mostly on backend and a lot of other stuff . However , I feel I should focus on one Front End or rather master one framework, since I have over the course of my (short) career have developed an lot of inclination towards the field. After a botched up interview ,looking for some thoughts on this. I do want to add that the wonderful HN has been instrumental in making me decide to pursue Front end Dev.