Sometimes you need to display content inside a page element that may be too wide to fit in the available space.
A scrollbar may appear automatically at the bottom of the wide page element, but if the content is also very tall, like for instance when you have a long article, the user may not see the bottom scrollbar, and so he may not be able to scroll the content sideways.
Read this article to learn about a solution to make a scrollbar also appear at the top of the wide page element.