Content Font doesn't display

Hi,

I am writing my content in Thai Language.
However, after i change and use this theme my single post content font becomes unreadable. The title and font page has no problem though

This isn’t fixed even i change back to another theme

Please Help

Example:
https://www.kao-it.com/2016/02/03/yahoo-%E0%B8%82%E0%B8%B2%E0%B8%94%E0%B8%97%E0%B8%B8%E0%B8%99%E0%B8%A2%E0%B8%B1%E0%B8%9A-%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%81%E0%B8%B2%E0%B8%A8%E0%B8%9B%E0%B8%A5%E0%B8%94%E0%B8%84%E0%B8%99%E0%B8%87/

Regards,
Adisorn