问题
I have a header and content area and it will be like a normal site. But whenever you scroll the page, a shadow image will appear in the bottom of the header (header height will be approx. 200px.). Content part will be scrollable and header will be fixed. Shadow image will disappear while you scroll back to top. The shadow image will appear only when a user scrolls the page. Please let me know how I can do this.
For example, please check http://mashable.com and go to any article. Whenever you finish the article, a popup from right side will appear. And similarly, when you scroll up, right popup disappears. Whenever right box appears, the rest content is scrolling behind it.
回答1:
I found this - http://jsfiddle.net/3cRe5/
does this solve your problem?
来源：https://stackoverflow.com/questions/7833843/fixed-header-with-shadow-image-on-scroll-with-scrollable-content-area