fix event links

index.php

@@ -137,7 +137,7 @@ $v = file_get_contents($VISITORS_FILE);
 						<tr>
 							<th scope="row"><?=format_event($event)?></th>
 							<td><?= htmlspecialchars($event->summary) ?></td>
-							<td><a href="<?= $first_event->url ?>">Details</a></td>
+							<td><a href="<?= $event->url ?>">Details</a></td>
 						</tr>
 					<?php endforeach ?>
 					</tbody>