BEFORE: body overflow:hidden, child overflow:auto Scroll this list on mobile. The address bar will NOT collapse because the browser only collapses its chrome when the document body scrolls, not when a child element scrolls.
/* Exact pattern used by Flutter web */
html, body {
  overflow: hidden; /* body never scrolls */
}

#scroll-container { /* like <flutter-view> */
  position: fixed;
  overflow-y: auto; /* child scrolls */
}

Scroll down — address bar stays stuck