Every other page here keeps its CSS inside the HTML file. This one links to a separate stylesheet:
<link rel="stylesheet" href="extra.css">
So the browser must fetch extra.css as well. In the Network tab
its Type is stylesheet, not png. The green bar
down the left of this paragraph and the different heading colour come from that
second file. If the request for it failed, the words would still be here —
just plain.
This paragraph is styled by the external file.
Anything a page mentions gets its own request: images, stylesheets, JavaScript files, fonts, videos. One file, one request.