JSFiddle - React, Tailwind, and code Playground

HTML

<table class="action_table">
   <thead>
    <tr class="header_row">
     <td>Header Item</td><td>Header Item 2</td><td>Header Item 3</td>
    </tr>            
   </thead>
   <tbody>
    <tr class="data_row">
     <td>Data Item</td><td>Data Item 2</td><td>Data Item 3</td>
    </tr>
   </tbody>
  </table>

CSS

.action_table {border-collapse:collapse;}
.action_table thead {border-bottom:10px solid #EEE}