Find scrollable elements

The page has a scrollbar but you don't know which element on page creates that scrollbar.
The Firefox Developer Tools allows us to see all elements causing overflow.

• In Firefox, open its Developer Tools
• Under the Inspector tab, if an element has a scrollbar (by using either overflow: scroll or overflow: auto but the content is longer than the element dimension), it will be shown with a scroll badge.

In the following screenshot, the highlighted element is displayed with the scroll badge indicating that it produces the scrollbar. Clicking the scroll badge will reveal the associate element.