Multiple bug fixes

【Contents of the fix】
■Fixed a bug where eye catching images could not be set on fixed pages.
■Changed the background color of the ranking widget.
■Added annotations for the speed-up function.

The following are the files that have been modified for this update.
【Modified file】
admin/inc/acceleration.php
functions.php
languages/ja.mo
languages/ja.po
pagebuilder/assets/admin/js/admin.js
style.css