I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
So when we have a look at the first div in the dev tools (the one under script), we will see that it has an id of fcc_test_suite_wrapper.
So my best guess is that is has something to do with the code of the script, that’s why I go to the URL of the script and search for fcc_test_suite_wrapper, we’ll see that the script actually adds a div with this id as a wrapper for the test suite to our codepen.
And because it is a div, the custom div CSS also works for this div.