Aaaaaaaaaaaaaaand this is what happens when you have people who don’t understand the technology work on one layer of abstraction, using inefficient frameworks to build things that could be built better with just a little skill and hard work, with no incentive or curiosity to care about any of the thousand other layers of abstraction:

youtube.com is literally more than 50% invalid HTML.

Nice work!

I’m guessing their unit tests don’t include running the output through a HTML validator.