In CSS you can set an element to be invisible. That means the element still takes up space on the page but it cannot be seen.
Open static.html and save it as visibility.html. View the page in a browser to remind yourself what it looks like. In your editor add this one attribute to the ruleset for #first in the embedded style sheet:
View the page again and the div should be invisible but the space it was in is still reserved. The opposite of hidden is visible which is the default.