Mobile not responsive

My website is not responsive with mobile screen only.
The actual screen is bigger than the website screen.
May you help me fix the problem?
My website: https://pokestop.com.vn
You can see the picture here:
https://drive.google.com/file/d/0B6hCeFvDbWTuenNxMHhjRkpfODQ/view?usp=sharing
Thank so much!