How does the "row" in Bootstrap 3.3.7 lead to the appearance of a horizontal scroll bar?

edit

The "row" in Bootstrap 3.3.7 has a default horizontal padding of 15px on each side. This means that the total width of a row is 100% + 30px (15px on each side).

If the content inside the row exceeds the available width of its container, the horizontal scroll bar appears to allow the user to scroll horizontally and view the content that is hidden. This can happen if the content of the row is too wide, or if the container itself has a fixed or limited width that is smaller than the row.

To prevent a horizontal scroll bar from appearing, it is recommended to ensure that the total width of the row and its contents does not exceed the available width of the container. This can be achieved by either reducing the width of the row or its contents, or by increasing the available width of the container.