function resize() {
  menu = document.getElementById('menu');
  submenu = document.getElementById('submenu');
  main = document.getElementById('main');
  
  menu.style.height = main.offsetheight;
  submenu.style.height = main.offsetheight;
}

function hide(id) {
  tag = document.getElementById(id);
  tag.style.display = 'none';
}

function show(id) {
  tag = document.getElementById(id);
  tag.style.display = '';
}

function focus(id) {
  tag = document.getElementById(id);
  tag.focus();
}