HTML table sticky headers using CSS

table thead:before {
  content: '';
  position: absolute;
  width: 100%;
  top: 0;
  border-top: 2px solid;
}

table thead {
  position: sticky;
  top: 0;
}

table thead:after {
  content: '';
  position: absolute;
  width: 100%;
  bottom: 0;
  border-bottom: 1px solid;
}