Fixed errors and other issues displayed in debug mode

【Contents of fix】
■Fixed the Notice error displayed in debug mode.
■Added support for PHP 7.2.0 (fixed deprecated error)
■Fixed a bug where the fixed footer bar for smartphones overlaps with the back button.

The following are the files that have been modified for this update.
【Corrected files】
functions/header-logo.php
page/template1.php
page/template2.php
page/template3.php
page/template4.php
widget/ad.php
widget/category_list.php
widget/google_search.php
widget/menu_category_list.php
widget/recent.php
widget/styled_post_list1.php
widget/styled_post_list2.php
header.php
page-nosidebar.php
style.css

For more information, please visit the AGENT (tcd033) download site for purchasers.