Did I indent correctly? This image is from Learn HTML page 6
Indentation is a direct signal of nesting. The DIV is a sibling of the H1, so not nested; how the H2, H3, H3 are nested in the DIV.
<h1></h1> <div> <h2></h2> <h3></h3> </div>
It looks like the intent is to nest the Species and Features under the H2, About Brown Bears. That would need another container.
<h2>About Brown Bears</h2> <div> <h3></h3> <p></p> <h3></h3> <p></p> </div> <h2>Habitat</h2>
Likewise would follow.
Study the parent-child-grandchildren aspect of HTML document structure. Master this concept and CSS and JS will be a cakewalk.
Thank you for taking the time to explain, Roy!