I mean, I wish I could use a navigation bar on the bottom of my web app, but on ios touching that area springs back the browser chrome and on chrome pinning something at vh will place it out of the screen when the address bar is visible.
Here's a fix and description of the issue, but yes. The bottom of the screen will take trial and error. I've been messing around with fullscreen modals for interactive content, and iOS is the main problem, 100vh != 100% != position: absolute; bottom = 0; top = 0;