html {
    filter: grayscale(50%);
    -webkit-filter: grayscale(50%);
    -moz-filter: grayscale(50%);
    -o-filter: grayscale(50%);
}

#mourning-ribbon {
  position: fixed;
  top: 0;
  left: 0;
  width: 150px;
  height: 150px;
  background-image: url('https://www.en.kku.ac.th/web/mech/wp-content/uploads/sites/10/2026/06/black_ribbon_top_left.png');
  background-size: contain;
  background-repeat: no-repeat;
  z-index: 9999;
  pointer-events: none;
}