I think I found 2 little issues in the Sparkling theme.
If you check https://colorlib.com/sparkling/bad_url (404.php theme page), some sections on the page doesn’t have popper margins or padding. As a result, some H2 title are very close the the previous content.
In comments area on single posts, if the pagination is enabled for comments, “Older posts” and “Newer comments” are floated to right or left, but not cleared by other content. As a result, the first comment and the title “Leave a comment” are displayed between the 2 buttons, or if only 1 of the 2 buttons is displayed, first comment and the mentioned title are displayed on the right/left of “Older/Newer comments” button.