Multiple bug fixes / support for WP5.8 widget block editor

【Contents of the fix】
■Adjusted the display timing of the load screen “Circle”.
■Support for the WordPress 5.8 widget block editor
■Adjusting the display position of the top page header content navigation when displayed on a smartphone
■Adjusting the style of tabbed content when viewed on a smartphone
■Fixed a bug where the image on the top page “Service List” would not be displayed depending on the hover effect setting.
■Fixed a layout error caused by the “[TCD] Banner List” widget.
■Fixed the display of the navigation image when the slider type is set to “Video” or “YouTube” in the top page header content.

【Modified files】
css/responsive.css
functions/loader_css.php
languages/ja.mo
languages/ja.po
widget/banner.php
front-page.php
functions.php
header.php
style.css