docs: embiggen landing page code

A more cromulent font size.

docs/index.html

@@ -25,7 +25,7 @@ layout: default
 <section class="d-flex flex-justify-center container-xl">
   <div class="mt-6">
     <h1 class="h000-mktg mt-6 mr-6">Catalyse your Web Components</h1>
-    <div class="d-flex">
+    <div class="d-flex f4">
       <div class="mt-4">
         {% highlight html %}
 <div data-controller="hello">