I want to change window.innerWidth and window.innerHeight to a specific size in device pixels, not CSS pixels.

I tried this:

window.addEventListener("resize", function() {
  if (window.confirm("Do you want to change this window's inner Size?")) {
    let x = window.prompt("Width:");
    let y = window.prompt("Height:");
    let r = window.devicePixelRatio;
    window.innerWidth = x / r;
    window.innerHeight = y / r;
  }
});

but the size of the new window doesn't match the given values.

For example, if I enter 1000 for width and height each, I get a window with an inner height of 1005 and an inner width of 989 device pixels.

Any idea how I can change the inner size of a window precisely?