chrome/browser/resources/sync_internals/events.html

<style>
#sync-events-table,
#sync-events-table th,
#sync-events-table td {
  border: 1px black solid;
}

#sync-events-table {
  width: 100%;
}

#sync-events > tr {
  vertical-align: top;
}
</style>

<table id="sync-events-table">
  <thead>
    <th>Time</th>
    <th>Submodule</th>
    <th>Event</th>
    <th>Details</th>
  </thead>
  <tbody id="sync-events">
  </tbody>
</table>

<script src="chrome://sync-internals/events.js"></script>