Improve blog setup - Use post title in banner. - Add native.css for testing syntax highlighting.

src/routes/blog/[slug].svelte

@@ -58,10 +58,9 @@
     <title>{post.title}</title>
 </svelte:head>
 
-<Banner/>
+<Banner title={post.title}/>
 
 <main class="container">
-    <h1>{post.title}</h1>
     <section>
         {@html post.html}
     </section>