* {
  box-sizing: border-box;
}

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

th, td, tr {
  border: 1px solid black;
  border-collapse: collapse;
  padding: 0px;
  margin: 0px;
  text-align: center;
  width: 50px;
  height: 20px;
}