This is the <div> element which will host the stack created by Button 1.
Button 2 removes the Button 1 stack, wherever it is placed on the page.
Clicking Button 3 will convert this <div> element into a stack of its own, making all the child elements (these 4 <p> tags) scrawl elements.
After clicking Button 4, creating a stack with button 1 will force that stack to be added to the end of the web page. You will no longer be able to turn this <div> element into a stack because it will no longer exist.