Multiple bug fixes

【Contents of the fix】
■【Mac】Fixed a bug that the thickness of Japanese and European characters may be displayed differently when using some fonts.
■Fixed an error regarding the login judgment in the comment section.
■Social Button Type 5 (Official Button) “Facebook Like Button” specification change.

The following are the files that have been modified for this update.

【Modified file】
bookmark.php
comments.php
editor-style.css
functions/custom_page_link.php
functions/update_notifier.php
japanese.css
style.css