要停止鼠标移动效果并将元素带回到单击第二个按钮时的起始位置，可以通过关闭鼠标移动并使用函数将元素放回其所属位置来完成。

// Initialize a variable to track whether the mousemove effect is active
var isMousemoveActive = false;

// Function to reset the elements' positions to their original state
function resetPositions() {
  // Use TweenMax to smoothly reset positions
  TweenMax.to(".d, .bg", 1, { x: 0, y: 0 });
}

// Button 1 click handler
$('.button1').click(function () {
  // Start the mousemove effect
  isMousemoveActive = true;

  // Attach the mousemove event to the section
  $('section').mousemove(function (e) {
    if (isMousemoveActive) {
      // Apply parallax effect
      parallaxIt(e, ".d", -12.5);
      parallaxIt(e, ".bg", -3.75);
    }
  });
});

// Button 2 click handler
$('.button2').click(function () {
  // Stop the mousemove effect
  isMousemoveActive = false;

  // Detach the mousemove event from the section
  $('section').off('mousemove');

  // Reset the positions of .d and .bg elements
  resetPositions();
});

// Function to apply parallax effect
function parallaxIt(e, target, movement) {
  var $this = $('section');
  var relX = e.pageX - $this.offset().left;
  var relY = e.pageY - $this.offset().top;

  // Use TweenMax to smoothly apply the parallax effect
  TweenMax.to(target, 1, {
    x: (relX - $this.width() / 2) / $this.width() * movement,
    y: (relY - $this.height() / 2) / $this.height() * movement,
  });
}