popup.html

<!DOCTYPE html>
  <html>
    <head>
      <style>
        body{min-width: 300px;}
        h1 {font-size:13px;}
        #credits{font-size:9px;margin-top:10px}
        #donate{display:block;margin:5px auto;}
      </style>
    </head>
    <body>
      <h1>Share your Garmin Connect workout</h1>
      <p>If you &#128150; this extension please <a href="https://www.buymeacoffee.com/filippopisano" target="_blank">consider a donation to the author &#127866;</a></p>

      <div id="credits">Icons made by <a href="https://www.flaticon.com/authors/freepik" target="_blank" title="Freepik">Freepik</a> 
        from <a href="https://www.flaticon.com/" target="_blank" title="Flaticon">www.flaticon.com</a></div>
    </body>
  </html>