VisualViewport

const bottomBar = document.getElementById("bottom-bar");
const viewport = window.visualViewport;

function resizeHandler() {
  bottomBar.style.display = viewport.scale > 1.3 ? "none" : "block";
}

window.visualViewport.addEventListener("resize", resizeHandler);

const bottomBar = document.getElementById("bottom-bar");
const viewport = window.visualViewport;
function viewportHandler() {
  const layoutViewport = document.getElementById("layoutViewport");

  // Since the bar is position: fixed we need to offset it by the visual
  // viewport's offset from the layout viewport origin.
  const offsetLeft = viewport.offsetLeft;
  const offsetTop =
    viewport.height -
    layoutViewport.getBoundingClientRect().height +
    viewport.offsetTop;

  // You could also do this by setting style.left and style.top if you
  // use width: 100% instead.
  bottomBar.style.transform = `translate(${offsetLeft}px, ${offsetTop}px) scale(${
    1 / viewport.scale
  })`;
}
window.visualViewport.addEventListener("scroll", viewportHandler);
window.visualViewport.addEventListener("resize", viewportHandler);