fix(_index): remove large-bold class from Advanced content <h> tag

According to issue #420 , tags should only have colour and padding classes

app/routes/_index.tsx

@@ -45,7 +45,7 @@ export default function App() {
         <WidgetStampy />
 
         <div className="padding-bottom-80" />
-        <h3 className="grey large-bold padding-bottom-32">Advanced content</h3>
+        <h3 className="grey padding-bottom-32">Advanced content</h3>
         <Grid gridBoxes={toc} />
       </div>
     </Page>