Fixed bugs

【Contents of fix】
■WP5.6 support (for jQuery version upgrade)

The following files have been modified for this update.
【Modified file】
admin/inc/basic.php
admin/js/my_script.js
functions.php
functions/head.php
functions/ogp.php
js/header_fix.js
js/header_fix_mobile.js
style.css

【Added files】
js/jquery.easing.1.4.js