Solved Page content area seems shifted

Hello,

I am new to using DIVI, please let me know if more element are required to diagnose my issue

I am having an issue where my "Content Area" (on a Page editor) is shifted to the right without any custom CSS applied or horizontal offset, I am trying to find the issue but can't solve this..
Here is what I found so far :
In the Divi builder editor, I have colored the "Content Area background color" in red, to be able to see what place the content occupies :

Nothing wrong in the picture above.

However, in the graphical editor view aswell as on the site preview, the background content area does not start at "left align" of the page and this get me in throuble when attempting to center content:


Here is what happens when I apply an horizontal offset to the Grey/black section left aligned with content Area :


Can someone guide me on what could go wrong here ? I was thinking there was some sort of "Default page layout sidebar", but I haven't noticed such.
I would like the red area to take 100% of the page's width.

Thank you in advance!

 

Could not edit the topic but yes, created the item too quickly, it's due to side menu CSS