Multiple bug fixes

【Contents of fixes】
■Added support for WP5.6 (jQuery version upgrade)
■Fixes the application of h1 tag.
■【Mac】Fixed a bug that Japanese and European characters were displayed with different thickness when using some fonts.

The following files have been fixed in this update.
【Modified file】
admin/css/editor-style-02.css
admin/css/editor-style-03.css
admin/css/editor-style.css
admin/js/my_script.js
archive-campaign.php
archive-menu.php
archive-news.php
archive-staff.php
archive-voice.php
functions.php
functions/head.php
functions/logo.php
functions/ogp.php
header.php
index.php
page-lp.php
page-noside.php
page-schedule.php
page.php
pagebuilder/assets/css/pagebuilder.css
single-menu.php
single-staff.php
style.css

【Added files】
js/jquery.easing.1.4.js