无JS实现的图片切换，CSS图片幻灯片切换特效，同时也实现了说明文字的动画效果，幻灯片上下切换，带播放进度条，进度条走到头-JS no picture switch, the CSS picture slide transition effects, as well as descr iptive text animation effects, slide switch up and down, with a playback progress bar, progress bar went t