类似以上的图片，根据图片的总长度和图片总数进行计算

<div class="frogeggitem"></div>.frogeggitem {width: 900rpx;height: 1000rpx;background: url('https://frog-skin.haoxgame.com/status2/frog/frogegg.png')no-repeat;background-size: 21600rpx 600rpx;animation: frgJump 1s steps(24) infinite;animation-direction: normal;margin-left: -110rpx;margin-top: -150rpx;margin-bottom: -490rpx;
}