URL: https://www.mobilesuica.com/
Browser / Version: Firefox 54.0
Operating System: Windows 10
Problem type: Something else - I'll add details below

Steps to Reproduce
Mobile Suica site for desktop browser doesn't support Firefox.

1. Navigate to: https://www.mobilesuica.com/

Expected Behavior:
Login content is shown.

Actual Behavior:

The following error is shown. It means that this site doesn't support current browser.
"ご利用のブラウザでは正しく画面が表示されない可能性がありますのでこのサイトをご利用できません。 "

From webcompat.com with ❤️