debug_extension/web/static_assets/inspector_panel.html

<!DOCTYPE html>
<html>
  <head>
    <link
      rel="stylesheet"
      href="material.indigo-blue.min.css"
      type="text/css"
    />
    <link
      rel="stylesheet"
      href="http://fonts.googleapis.com/css?family=Roboto:300,400,500,700"
      type="text/css"
    />
    <link rel="stylesheet" href="styles.css" type="text/css" />
  </head>

  <body id="panelBody" data-panel="inspector" class="dark-theme">
    <div id="landingPage" class="mdl-layout mdl-js-layout">
      <header class="mdl-layout__header">
        <div class="mdl-layout__header-row">
          <span class="mdl-layout__title">Flutter Inspector</span>
          <div class="mdl-layout-spacer"></div>
        </div>
      </header>

      <div class="mdl-grid">
        <div class="mdl-cell mdl-cell--12-col">
          <div class="dart-card inspector-card mdl-card mdl-shadow--2dp">
            <div class="mdl-card__title"></div>
            <div class="mdl-card__supporting-text">
              The Flutter Inspector allows you to inspect the widgets in your
              Flutter app.
            </div>
            <div class="mdl-card__actions mdl-card--border">
              <button
                id="launchDebugConnectionButton"
                class="mdl-button mdl-js-button mdl-button--raised mdl-js-ripple-effect mdl-button--accent"
              >
                Launch Inspector
              </button>
              <div
              id="loadingSpinner"
              class="mdl-spinner mdl-js-spinner is-active hidden"
            ></div>
            </div>
          </div>
        </div>
      </div>
    </div>

    <div id="iframeContainer"></div>
    <div id="warningBanner" class="snackbar snackbar--warning">
      <span id="warningMsg">Error.</span> If something is broken, please
      <a
        id="bugLink"
        href="https://github.com/dart-lang/webdev/issues/new"
        target="_blank"
        rel="noopener noreferrer"
        >file a bug.</a
      >
    </div>

    <!-- Load script: -->
    <script src="../panel.dart.js"></script>
  </body>
</html>