Welcome to the new Boards.ie platform - Version 1.0 :)

Also, now when I click on the three lines menu at the left of the bar all the categories are expanded and can't be collapsed. Android / Edge and Chrome

Top bars normally appear dynamically - there when you land on the page, disappear when you scroll down, appears when needed again (ie, scroll up or touch screen without scrolling)

It's pretty standard for mobile

You shouldn't - as I said if implemented correctly it reappears dynamically as you gesture up/touch. A thin top bar with hamburger menu/title/search/profile icons could be always visible then the dynamic menu visible as needed. Here, both are permanently visible

I've a large phone screen but loads of people don't.

PS, i've just noticed the permanent top bar (double the size it should be) is gone now! It's changed colour (I like) but completely disappears as before.

I think this isn't the final state of it, I'd guess they are updating as they go through the day.

Maybe behind the scenes, the site can adjust to phone model/screen size (ie small screen no huge fixed bar) - that would be ideal. I understand the need for not scrolling the whole way back up which is ridiculous - on desktop there still isn't a 'back-to-top' button and each thread page is set as something like 30 posts and there's loads of whitespace so for mouse users it's a scrolling chore.

Let's hope the final iteration caters to everyone and normal navigation specs!

This is what I get when I open the menu. Categories expanded and can't be collapsed. Android, every browser I've tried.

Same. I think it is being worked on live.

Top bar is back to persistent now and categories can be collapsed

If you look at e.g. the Irish Times website, that banner/ navigation bar at the top dissappears when scrolling down, but reappears when scrolling up - perhaps that could be done?