After placing post, my logo shift to the right !!!

Hello,

first time i work with everything (php/css/WORDPRESS/etc)
After getting the basics and learning WP i tried to use a theme and later to modify it. Everything OK so far.

Now i found a problem :

My logo (header) shift to the right side of my page after placing a comment……..! I tried many times to find the problem but i’m not that good in codes and cannot find it.

Also a strange thing is my search widget, it won’t stay in line, it is also shifted a little more to the right.
But thats from the first time of (from the beginning i started with WP and this theme.

Without problem logo : https://www.msjx.be
With logo problem : https://www.msjx.be/?p=1#comments

Please help a learning man !

Thanks, Martijn.