Extended Example
If we want to, we may even make the first-level heading <h1> appear smaller on screen than the subsequent headings, such as <h2>, for instance. The underlying structure remains intact, nevertheless.
Why would we ever want to do that, for instance? Well, we might want to emphasize the sub-headings <h2> in a series of pages that share the same first-level heading, like this in a series of pages about Little Miss Muffett:
page 1
<h1>Miss Muffett, the Mystery</h1>
<h2>Table of Contents</h2>
page 2
<h1>Miss Muffett, the Mystery</h1>
<h2>Who was Muffett?</h2>
page 3
<h1>Miss Muffett, the Mystery</h1>
<h2>Why was Muffett on the Tuffett?</h2>
etc.
Yes, we can adjust the headings with CSS for appearance sake while the underlying structure remains intact.