table {
  /* Not required only for visualizing */
  border-collapse: collapse;
  width: 100%;
}

table thead tr th {
  /* Important */
  background-color: #99bce8;
  position: sticky;
  z-index: 100;
  top: 0;
}

td {
  /* Not required only for visualizing */
  padding: 1em;
}

span {
  position: sticky;
  z-index: 10;
  top: 1px;
}