<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Details & Summary</title>

</head>
<body>
  <!-- <details> creates a native expand/collapse widget -->
  <details>
    <summary>Click to read more</summary>
    <p>This hidden content is revealed when the user clicks the summary.</p>
  </details>

  <details open>
    <summary>Open by default</summary>
    <p>Add the "open" attribute to expand it initially.</p>
  </details>
</body>
</html>