top: 0, left: 0 on a decoration image doesn’t stick the image to the top left corner of the container because it itself uses margin-top for positioning 
Plasmic’s default layout components are super weird
Yes unfortunately this is a limitation of the current way that gaps work, as long as you have set a gap then it uses margin to implement it in a cross browser way. I work around is that you can wrap it in another container that doesn’t have a gap and perform the absolute positioning with respect to that