frozen-column.css

td:first-child {
  position: sticky;
  left: 0;
  z-index: 1;

  animation-name: frozen;
  animation-duration: 1ms; /* Firefox needs this. */
  animation-direction: alternate;
  animation-timeline: scroll(inline nearest);
  /* Hide shadow in all directions except east. */
  clip-path: inset(0 -30px 0 0); /* 30px is matching the box shadow size. */
}

@keyframes frozen {
  from {
    box-shadow: none;
  }

  1%,
  100% {
    background-color: white;
  }

  to {
    box-shadow: rgb(0 0 0 / 10%) 10px 0 30px;
  }
}