Page aligment, how do i put my page in center when browsing in mobile?

I want to make my webpage responsive, so i used bootstrap. but when i see the page in a mobile (iphone 6/7/8 for example), all the content is left handed. i want it in the screen center. what am i doing wrong?

the page is:

https://ift.tt/356LjBS

help please! thanx