Background-image from customizer linked with aside-menu (DAWN THEME)

Store Design
1

Hi there, im trying to get this kind of landing-section with aside-menu and hover change image with it. (from eu.kith.com)

At the moment this is what i have: https://f0jfypzl040i0kcv-53196980409.shopifypreview.com

Script code used :

//megamenu hover
    let items = document.querySelector(".aside__nav").querySelectorAll("details");
    items.forEach(item => {
        item.addEventListener("mouseover", () => {
            item.setAttribute("open", true);
            item.querySelector("ul").addEventListener("mouseleave", () => {
                item.removeAttribute("open");
            });
            item.addEventListener("mouseleave", () => {
                item.removeAttribute("open");
            });
        });
    });

    //megamenu image show on hover
    $(".custom-mega-img").hover(function(){
        $(this).find(".megamenu-img").addClass( "active" );
    }, function(){
        $(".megamenu-img").removeClass( "active" );
    });

The problem right now is in the images shown with hover. Show all images, and that should only show one image chosen from the customizer.

We would then have to bind each image block to our details-id within our side menu.

Can someone show me the way to finish this section?

If its needed some file just tell me please! thanks in advance

2 
{{ 'section-aside-backgrounds.css' | asset_url | stylesheet_tag }}
{{ 'section-image-banner.css' | asset_url | stylesheet_tag }}