JSFiddle - React, Tailwind, and code Playground

HTML

<h1>Fixed &lt;thead&gt; Sandbox</h1>
<table>
  <thead>
    <tr>
      <td>Column 1</td>
      <td>Column 2</td>
      <td>Column 3</td>
      <td>Column 4</td>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
      <td>Data</td>
    </tr>
    <tr>
     ...

CSS

body {
    font-family: sans-serif;
    padding: 0.3em 0.6em;
}
h1 {
    font-size: 2em;
    margin: 0.6em 0;
}
h2 {
    font-size: 1.3em;
    margin: 0.6em 0;
}
table {
    border: 1px solid #ddd;
    width: 100%;
}
thead {
    background: #eee;
    display: block;
}
tbody {
    display: block;
    height: 15em;
    overflow: auto;
}
td {
    border: 1px solid #ddd;
    padding: 0.3em 0.6em;
    width: 0.1%;
}