如何让回收站滚动条始终可见？

#recycle-bin {
  height: 300px;
  overflow-y: scroll;
}

window.addEventListener('DOMContentLoaded', function() {
  var recycleBin = document.getElementById('recycle-bin');
  if (recycleBin.scrollHeight > recycleBin.clientHeight) {
    var scrollbar = document.createElement('div');
    scrollbar.style.width = '10px';
    scrollbar.style.backgroundColor = '#ccc';
    scrollbar.style.position = 'absolute';
    scrollbar.style.right = '0';
    scrollbar.style.top = '0';
    scrollbar.style.bottom = '0';
    recycleBin.appendChild(scrollbar);
  }
});