For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
<ul class="nav nav-pills pull-<?php if ($lang->isRTL()) : ?>right<?php else: ?>left<?php endif ?>">
i.icon-delete.icon-remove::before {
content: "I";
}