HTML and CSS are two separate technologies that work together in every web page. HTML consists of the elements like
<div> that give your page structure. It’s important because without these elements, your browser would just see a big block of text and not know what to do with it. CSS tells the browser how to style these elements, and without this all the user would see is a big block of text.
One point that isn’t yet covered well in the early curriculum here is that putting
style in HTML is a really, really, really bad idea.
<h1 style="color: blue">What is this nightmare scenario?!?</h1>
It’s always better to use classes or ids. I forked your pen and moved all of the style to the CSS portion. See if you can spot the differences in the code.