use native tags in article header partials

layouts/partials/article-meta.html

@@ -1,12 +1,12 @@
-<div class="article-meta">
+<section class="article-header">
-    <h1 class="center-text">{{ .Title | markdownify }}</h1>
+    <h1>{{ .Title | markdownify }}</h1>
 
     {{ $authors := .Params.authors | default (slice .Site.Params.defaultAuthor) }}
     {{ $primaryAuthor := index $authors 0 }}
 
     {{ with $primaryAuthor }}
         <a class="center-text" href={{ printf "/%s/%s" "authors" (urlize .) }}>
-        <h2 class="center-text">{{ . }}</h2>
+            <h2>{{ . }}</h2>
         </a>
     {{ end }}
 
@@ -18,4 +18,4 @@
 
 	{{ partial "header-image.html" (dict "image" (.Resources.GetMatch .Params.featured.url) "alt" .Params.featured.alt) }}
 
-</div>
+</section>

layouts/partials/header-image.html

@@ -1,4 +1,4 @@
-<img class="shadow large-image"
+<img class="shadow featured"
 	{{ with .image }}
 		srcset="
 		{{ (.Resize "320x q30").RelPermalink }} 500w,