popup.html

<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>Unload Some Tabs Popup</title>
    <style>
html {
  font-family: "Segoe UI", "Lucida Grande", Tahoma, sans-serif;
  font-size: 100%;
  min-width: 200px;
  text-align: center;
  background-color: #dcf;
  color: #203;
}
button {
  margin: 5px;
  padding: 5px;
  /* (default background pattern instead of background-color) */
  color: #102;
}
    </style>

    <script src="popup.js"></script>
  </head>
  <body>
    <div id="status"></div>
    <button id="unloadthis">Unload this tab</button>
    <button id="unloadnonpinned">Unload all non-pinned http(s) tabs</button>
  </body>
</html>