function startDrag(e) {
activeImg = e.target;
offsetX = e.clientX - activeImg.offsetLeft;
offsetY = e.clientY - activeImg.offsetTop;
activeImg.classList.add("dragging");
activeImg.style.zIndex = 1000;
}
function endDrag(e) {
if (!activeImg) return;
const aRect = imgA.getBoundingClientRect();
const bRect = imgB.getBoundingClientRect();
const overlap = !(
aRect.right < bRect.left ||
aRect.left > bRect.right ||
aRect.bottom < bRect.top ||
aRect.top > bRect.bottom
);
if (overlap) {
imgA.style.display = "none";
imgB.style.display = "none";
imgC.style.display = "block";
}
activeImg.classList.remove("dragging");
activeImg = null;
} 
