#toolbar-administration {
  position: fixed !important;
  top: 0;
  width: 100%;
  z-index: 501 !important; /* Drupal's default is usually 500; 501 pushes it above almost everything */
}

/* Ensure the sub-menus (trays) also stay on top */
.toolbar-tray {
  z-index: 501 !important;
}

/* If you are logged in and the toolbar is present */
body.user-logged-in {
  margin-top: 39px !important; /* Height of the main black bar */
}

body.user-logged-in.toolbar-tray-open {
  margin-top: 79px !important; /* Height of bar + sub-menu tray */
}