Pop theme Error

[abdulra7man9]

Regarding Pop theme
http://pop.osclassdemo.com/demo/


There is a problem I found:
When I open this theme on my I-Phone or on my chrome browser, I found that the posts cover each others.

The posts at the top of the page looks fine, but when I scroll down till the bottom of the page, the posts start covering each other.

Is there any suggestion on how to fix this error,


Thank you