this box has been absolutely positioned
The code you are reading. is placed in a container nested within another with a white background. This is container has been given no width nor does it have any margins so that it starts at a position dictated by the margins of the container in which it sits. It expands to fill the rest of the page
You can write to the right of this container but not to the right You would need to nest another container in the bank space with the same background as this container.
The written content can continue below the nested container