html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
  display: table;
  width: 100%;
}

body {
  display: table-cell;
  vertical-align: middle;
  text-align: center;
}

table {
  margin-left: auto;
  margin-right: auto;
}

td {
  border: 10px solid black;
}