Finding the right single page theme

Hi!
New wordpress user here. Been using Drupal for a couple of years but now I have to make a simple page quickly which needs the auto-update functionality that wordpress offers, so here I am.

My question in short: I need a customizable responsive single page theme. With the ability to create my own sections which I can code more or less myself.

I am having trouble finding a theme which is customizable enough for my needs. I found several that look nice (Illdy, Parallax one, Shapely etc.), but I feel constrained by them as none of them fits the page I need to make perfectly and I can’t seem to customize them enough. Using the first page as the major container won’t do because it doesn’t go all the way to the edges of the window (background colors will have a big gap which looks strange). I don’t need a theme that looks great and which offers the perfect layout from scratch, these things I can fix but I’m not sure how to create the sections if I were to go on and make my own theme.

I’d appreciate any help:)