.abc {
  display: table-cell;
  text-align: center;
  vertical-align: middle;
  width: 500px;
  height: 500px;
  background-color: #000;
}
.abc * {
  vertical-align: middle;
}

p {
  font-size: 3rem;
  color: #fff;
}

small {
  font-size: 1rem;
  color: #00aa00;
}