JSFiddle - React, Tailwind, and code Playground

HTML

<table class="mainTable">
<tr>
  <td>
    <table class="slaveTable">
      <tr><th>Velikost</th></tr>
      <tr><td>XS</td></tr>
      <tr><td>S</td></tr>
      <tr><td>M</td></tr>
      <tr><td>L</td></tr>
      <tr><td>XL</td></tr>
      <tr><td>XXL</td></tr>
      <tr><td>XXXL</td></tr>
    </table>
  </td>
  <td>
    <table class="slaveTable">
      <tr><th>Hruď</th></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
    </table>
  </td>
  <td>
    <table class="slaveTable">
      <tr><th>Pas</th></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
    </table>
  </td>
  <td>
    <table class="slaveTable">
      <tr><th>Délka</th></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
      <tr><td>86-94</td></tr>
    </table>
  </td>
</tr>
</table>

CSS

table.mainTable td {
  padding: 0 7px;
  border-right: 1px solid grey;
  text-align:center;
}

table.mainTable td:last-child {
  border-right: 0;
}

table.mainTable table.slaveTable td {
  padding: 0 7px;
  border-right: 0;
  border-bottom: 1px solid grey;
}

table.mainTable table.slaveTable th {
  border-bottom: 1px solid grey;
}