I have a design that I’m trying to create where the background behind the menu is an odd shape. It looks like this:

The image beneath the menu area will be in LayerSlider.
I’ve almost managed to create it, though I don’t know if I’m going about it the right way, and it’s not quite where I need it to be. Here’s what it looks like on my dev site:

I’ve accomplished it by putting an image of the odd-shaped pink area in the container behind the menu. (And I’ll use a different image on mobile that is much smaller and contains a hamburger menu icon). But, as you can see, I can’t get the pink to bleed below the header and under the LayerSlider image.
Can you help, please?