The ground is beneath you too but you would fall to your roasty death in the center of the planet if it wasn't there, and if you have a gaping hole in your knowledge base then identifying and resolving it before some portion of the companies' success is resting on your too-narrow shoulders is a good idea.
I'd much rather work with and for any of the people replying than you.
Nobody cares about text-size-adjust and other such nonsense. It doesn't materially change anything.
If someone said that to me in an interview my next question would be "Why did you apply for a senior frontend dev role then?"
Nobody cares about text-size-adjust and other such nonsense.
Senuor frontend devs do care about that, because it affects the display quality, accessibility, and readability of a web app on a mobile device. If you get text size wrong on a site like Amazon or Twitter you could push tens of thousands of people to stop engaging with the site. Imagine if the "Buy Now" text on a button overflowed because the font was too big so it read "Buy no" instead. That would have an impact on revenue.
I want to hire you, not someone who's never really thought about what's going on. These questions are just a trick to force someone to step out of the box and go deep into some fundamental web concepts. It's not about memorizing some HTML tags, it's about knowing why they exist.
edit: This is just in the hypothetical scenario I'd be hiring a senior frontend web developer. You generally only need maybe 30% of those, the rest I can get trained on developing features within 3 months after finishing a 10 week bootcamp. I wouldn't bother asking them how UTF-8 works, I just explained what the word "encoding" means to a junior who'se been outpacing me for the past 3 months. The person who reviews their merge request should definitely know what UTF-8 is.