Help ! Freestyle line piercing objects

Hello guys I am digging Blender everyday and … I am experiencing the problems everyday xD
Most of the time the problem really came from me not from the innocent blender
and I hope again, I am the one making the the mistake

Today I am posting this post to ask you why this is happening
I’ve put a slope next to a cuboid and I’ve rendered it and there is a suspicious line
rendered inside the slope, I’ve done some little investigation and found out that it was
the edge of the cuboid rendered through the slope (lol?)



to find a solution I’ve moved the slope in X axis

Left - > Right
Right - > Left

and I’ve realized that … no matter the distance of the movement
sometimes the edge of the cuboid is rendered through the slope
and sometimes nope !
(yeah… from where the edge of the cuboid was rendered I move just a little
than I don’t see the edge of the cuboid anymore and I move again just a little again in
same direction and I see the edge again …)

I need help guys I don’t want to see
the edge of the cuboid rendered through the slope…
Thanks in advance !