Thank you for your help.
I add the code to the CSS file, and it worked well.
I figure out the reason why it disappear on particular PCs.
That is I set the Limit API Requests Per Client on the setting on wordpress plugin’s Advanced Features, but I though that is for limit just one hour for example.
The problem is once it come to the limit, it won’t recover on same PC.
Is there anyway to resolve the problem?
Thank you for the answering.
I figured out the problem.
I didn’t write “wp_footer();” on file footer.php, so that the plugin didn’t be loaded.
A sentence solved the whole problem.
