Margin errors I need some help with

Dear colleagues,

on my website (http://suvelfabryk.nl/sqsp) I am working on a new homepage. I have unfortunately a lot of challenges with lining everything out the way I want. As you can see on the website on both gallery blocks (one with 2, the other with 4 photo's) I have still some background that is visible. I would really like it everything would be seamless. I just have no clue how to do it with the new grid system. I've added a picture of what I want to achieve. On the link you see what it looks like now. The pages is not visible yet but it can be found at /sqsp. I would really appreciate some input as I'm struggling a bit to see how to get here 🙂

Thanks in advance!

btw: I have found that I can do it if I don't do it with sections. But it does "break" the website more when I need to do changes..

Fix it myself by adjusting the margins on website level.