So when I open the document (before), the problem with formatting already starts with the line:
<a class="btn btn-outline-cms-gray" href="index.php?page=communication-systems&submenu=<?php echo $_GET['submenu']; echo (isset($langlink) AND $langlink) ? '&'.$langlink : NULL; echo (isset($admin_site) AND $admin_site) ? '&'.$admin_site : NULL; ?>" role="button"><?php echo translate_text('Zurück') ?></a>
But after I have formatted the content of the "href" by selection, the code looks like this:
<a class="btn btn-outline-cms-gray" href="index.php?page=communication-systems&submenu=<?php echo $_GET['submenu'];
echo (isset($langlink) and $langlink) ? '&'.$langlink : NULL;
echo (isset($admin_site) and $admin_site) ? '&'.$admin_site : NULL; ?>" role="button"><?php echo translate_text('Zurück') ?></a>
If this is the only issue, the document can be successfully formatted afterwards and looks like this:
<a class="btn btn-outline-cms-gray" href="index.php?page=communication-systems&submenu=<?php echo $_GET['submenu'];
echo (isset($langlink) and $langlink) ? '&'.$langlink : NULL;
echo (isset($admin_site) and $admin_site) ? '&'.$admin_site : NULL; ?>
" role="button"> <?php echo translate_text('Zurück') ?></a>
Perhaps it would make sense to put PHP first and HTML/REST second.