Update HTML to be more POSH

Switched divs for proper HTML tags.

layouts/partials/header.html

@@ -1,10 +1,10 @@
 
-<div id="sidebar">
-	<div id="site-title">{{ .Site.Title }}</div>
+<header id="sidebar">
+	<h1 id="site-title">{{ .Site.Title }}</h1>
 	<img class="w-48 mx-auto rounded-full border border-black" src="/imgs/logo_partial.png" alt="Logo for The Hive" />
-	<div id="nav">
+	<nav id="nav">
 		{{ range .Site.Menus.main }}
 		<a href="{{ .URL }}">{{ .Name }}</a>
 		{{ end }}
-	</div>
-</div>
+	</nav>
+</header>