COMMUNITY

Hi, everyone.
I'd be really happy if someone could help me out.

I'm creating chatbot here.
http://www.web-keiei.sakura.ne.jp/machidatsu02/services/

But when we see it with some kinds of smartphone,
the closing button isn't appeared.

Like this
https://www.evernote.com/l/AQPhMu2bp32o5xZmo6vW_ZSsQPt7CzTcCJU/

We notice this issue at least iPhone 7plus and iPhone 6s.

Is there any good ways to solve it?
Thank you.