table {
  border-collapse: collapse;
  margin: 1em auto;
}

thead th {
  background-color: #f5f5f5;
  font-weight: bold;
  border-bottom: 20px solid black;
  padding: 8px;
}

tbody td, th {
  border-bottom: 10px solid #ddd;
  padding: 8px;
}

table tr:last-child td {
  border-bottom: 3px solid black;
}

table tr:first-child th {
  border-top: 3px solid black;
  border-bottom: 3px solid black;
  background-color: #f5f5f5;
}