JSFiddle - React, Tailwind, and code Playground

HTML

<div style="height:100%">
<div>
This is the fixed header
</div>
<div style="overflow:auto;">
<table>
<tbody>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
  <tr><td>12345</td><td>67890</td><td>ABCDE</td></tr>
 ...

CSS

html, 
body {
    height: 100%;
}