The plugin is loading the stylesheet correctly, so that’s good news. (Line 232 of the source code for that page has the css file loading correctly.)
Unfortunately, the theme doesn’t put the date in the same span as the vertical bar before or after it, so I can’t modify my plugin to hide date and one of the bars. The fix is to modify your theme files, specifically single.php and to wrap both the date and the “|” after it in a span with the class “post-date.”
Line 15 in single.php currently looks like this: <div class="post-info"><span class="theauthor"><?php the_author_posts_link(); ?></span> | <span class="thetime"><?php the_time( get_option( 'date_format' ) ); ?></span> | <span class="thecategory"><?php the_category(', ') ?></span> | <span class="thecomment"><a href="<?php comments_link(); ?>"><?php comments_number();?></a></span></div>
You should modify it to look like this: <div class="post-info"><span class="theauthor"><?php the_author_posts_link(); ?></span> <span class="thetime post-date"><?php the_time( get_option( 'date_format' ) ); ?></span> | <span class="thecategory"><?php the_category(', ') ?></span> | <span class="thecomment"><a href="<?php comments_link(); ?>"><?php comments_number();?></a></span></div>
Never modify theme files from within the dashboard area, always use a text editor and FTP. Also, the best way to do this is always using a child theme, so that customization of the theme is not overwritten by updates.
Let me know if you need any more help!
Ben