JSFiddle - React, Tailwind, and code Playground

HTML

<table class=withCollapse>
  <tr>
    <td class=A>1</td>
    <td class=A>2</td>
    <td class=A>3</td>
    <td></td>
    <td></td>
    <td></td>
  </tr>
  <tr>
    <td class=A>1</td>
    <td class=A>2</td>
    <td class=A>3</td>
    <td class=A>4</td>
    <td></td>
    <td></td>
  </tr>
  <tr>
    <td class=A>1</td>
    <td class=A>2</td>
    <td class=A>3</td>
    <td class=A>4</td>
    <td class=A>5</td>
    <td class=A>6</td>
  </tr>
</table>

CSS

table {
  background-color: white;
  margin: 5px 5px 10px;
}

table.withCollapse{
  border-collapse: collapse;
}

td {
  width: 50px;
  height: 25px;
}

.A {
  border: 1px solid red;
  background-color: #eee;
}