Nice find. Only works if your menu doesn't autohide.

Sounds to me like you need to split things out. Use basic tools like Moqups and, Invision for testing basic interactions. When you're happy with how things are going then move to something like Framer where you can create more precise/end-ready interactions.

Trying to do all of that at once is just asking for an unattainable goal IMHO.

One that I find to work rather well is Folio.

What's nice about it over some of the cloud apps out now is the cost is a simple one time purchase. There's also a free viewer app for those that don't need to commit/manage the individual repositories.

How are extra small buttons larger than small?

You're welcome. Rather than try and explain it myself I'd check out https://zellwk.com/blog/why-vertical-rhythms/

I wouldn't try to be so pixel perfect and worry more about vertical rhythm.

And yes, browsers display line-height differently per font and per browser.

It's always been the case if memory serves correct though I haven't used Photoshop in years.

Not for me. First two fonts I tried to show how they can be different: http://dch.link/zTSlPjPCeJ/

Every font has its quirks. That's all it is from what I can see.

What do you need or want changed? What do other products have that contributes to a better workflow and production? Are the features that look "cool" actually useful for work or fun? Etc. Etc.

I think people need to look at questions like these before asking such a question.

As far as my opinion – I think the Surface Pro looks great but there's absolutely nothing that would make me a better web designer and developer.