Sticky element width

Hi! Thank you for your assistance with my first issue. I would like to ask about another matter.

At present, the width of the sticky menu is the exact width of the element. I know I can add a width element to the CSS so that it becomes the full screen, but I would actually just like for the menu to be 2 or 3 pixels longer on each side. The reason for this is because of the image on my Home page. It has a box shadow on it and when you scroll down and the menu overlaps the image, you can see the shadow a bit on the left side of the menu.

Is there any way to extend the sticky menu’s size by a few pixels on both sides? My content area is 1040px and I’ve tried changing the width of the menu to 1040px when sticky, but it only extends to the right and not the left.

Any assistance would be appreciated! Thank you.

The page I need help with: [log in to see the link]