Ask HN: Where to start learning web development in 2017?

Hi! My background: formal visual literacy/art instruction, but sadly with little hands-on experience with modern media. Experience in design mostly for print, passion for typography, played with Python and Arduino, done some websites for friends using Bootstrap. What I'm willing to accomplish: know Bootstrap and modern UI frameworks even better, understand how modern browsers work, study how to write HTML/CSS/Javascript that is up to date with the current standards. Where do I start? How can I catch up with the new things out there? Things change so fast and every tutorial I read seems to be either too vague to be useful, or too specific and already outdated. Thank you all!