offsetTop;
            // Traverse upwards until an `absolute` element is found or `elem`
            // becomes null.
            while (elem = elem.offsetParent && elem.style.position != 'absolute') {
                x += elem.offsetLeft;
                y += elem.offsetTop;
            }

            return { left: x, top: y };
        }
        // https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetTop
        const bbox = node.getBoundingClientRect();
        const offset = calcOffset(no