      panel.dfn = dfn;
        panel.top = window.scrollY + dfn.getBoundingClientRect().top;
        let panelRect = panel.getBoundingClientRect();
        panel.height = panelRect.height;
        if(main) {
            panel.overlappingMain = panelRect.left < mainRect.right;
        } else {
            panel.overlappingMain = false;
        }
    }
    // And finally position them
    for(const panel of panels) {
        const dfn = panel.dfn;
        if(!dfn) continue;
        panel.style.top = panel.top