Fixed multiple bugs

【Contents of the fix】
■Fixed a bug that articles without eye-catchers were not displayed in the “Announcements” section of the top page when viewed on a smartphone.
■Fixed an issue where the button color set in the theme options “Header Button Settings” was not reflected.
■Fixed a bug that the color setting was not reflected when selecting custom marker in theme options “Google Map Settings”.
■Fixed a bug that occurred when selecting YouTube in the top page slider.
■Fixed the bug that the layout of the top page “3 point box” may be broken in IE.
■Fixed the bug that the top page slider did not move smoothly in IE.
■Corrected the output to the browser tab.
■Added some wording to the theme options.

The following files have been modified for this update.
【Corrected files】
admin/inc/basic.php
admin/inc/options.php
css/responsive.css
functions/head.php
functions/seo.php
language/ja.mo
language/ja.po
template-parts/slider_ini.php
functions.php
style.css