Correct 'aestethic' to 'aesthetic'.

index.html

@@ -61,7 +61,7 @@ <h2 id="introduction">Introduction</h2>
 <em>just work</em>, at least that’s the goal. It’s semantic HTML,
 rendered as if we were back in the 70s.</p>
 <p>All right, but is this even a good idea? It’s a technical and
-creative challenge and I like the aestethic. If you’d like to use it,
+creative challenge and I like the aesthetic. If you’d like to use it,
 feel free to fork or copy the bits you need, respecting the license. I
 might update it over time with improvements and support for more
 standard elements.</p>