为什么隐藏地址栏时html { height:100% }不起作用？

function enterFullScreen() {
  var elem = document.documentElement;
  if (elem.requestFullscreen) {
    elem.requestFullscreen();
  } else if (elem.mozRequestFullScreen) {
    elem.mozRequestFullScreen();
  } else if (elem.webkitRequestFullscreen) {
    elem.webkitRequestFullscreen();
  } else if (elem.msRequestFullscreen) {
    elem.msRequestFullscreen();
  }
}

var lastScrollTop = 0;
window.addEventListener("scroll", function(){
  var st = window.pageYOffset || document.documentElement.scrollTop;
  if (st > lastScrollTop){
    window.scrollTo(0, 1);
  }
  lastScrollTop = st;
});