JSFiddle - React, Tailwind, and code Playground

HTML

<table class="mytable">
    <tr>
        <td>Col1</td>
        <td>Col2</td>
        <td>Col3</td>
        <td>Col4</td>
    </tr>
    <tr>
        <td>Col1</td>
        <td>Col2</td>
        <td>Col3</td>
        <td>Col3</td>
    </tr>
    <tr>
        <td>Col1</td>
        <td>Col2</td>
        <td>Col3</td>
        <td>Col3</td>
    </tr>
    <tr>
        <td>Col1</td>
        <td>Col2</td>
        <td>Col3</td>
        <td>Col3</td>
    </tr>
</table>

CSS

table.mytable
{ 
    
    border-collapse:collapse; 
}

.mytable td {
border:1px solid;    
}
.mytable tr:first-child td:nth-child(1){
border:1px transparent;    
}