usable H — min · toolbar shown (svh)
usable H — max · toolbar hidden (dvh)
width
Rotate to LANDSCAPE. First reading = toolbar visible (svh). Then SCROLL UP to collapse the toolbar — the "max" number grows; that's dvh. Take ONE screenshot after scrolling: the fixed top bar shows both min & max.
⬆︎ scroll until the browser toolbar collapses, then screenshot the top bar.