Thanks for the feedback. The Search API for HN is provided by Algolia. The action bar is of course hidden when scrolled. Noted down to add the pull to refresh function.
WhatsApp hasn't even updated their TOS in their site since 2012 and moreover Facebook can disable account only if someone "infringe other people's intellectual property rights" inside FB. This makes me wonder what made it in the first place to allow FB disable account for violating WhatsApp terms.
I would suggest you to check out Bootstrap. But if you need a more lightweight mobile-first solution, You can check out Cardinal Framework. There are also lot more available in this repo https://github.com/moklick/frontend-stuff#ui-frameworks