Seamless image scrolling (div + CSS)

We must have noticed that <marquee> does not scroll cyclically, so there are many alternative scripts, or IFRAME or JS output <marquee>. No matter how it is done, it is a little troublesome. The following is a simple implementation concept: A container demo that sets the width and hides content beyond its width. demo1 and demo2 are included in the demo, and demo1 is the scrolling content, demo2 is a direct clone of demo1. By constantly changing the scrolltop or scrollleft of demo1 to scroll, the original position is directly jumped back when rolling to the junction of demo1 and demo2 because demo1 is the same as demo2, therefore, we can't tell the beat moment to achieve the goal of "seamless" rolling.
Http://hi.baidu.com/cnaspnet/blog/item/52e40c46fcb6af096b63e5bc.html (from network)