style content header and headings

have the header and headings center aligned

assets/scss/_base.scss

@@ -59,6 +59,7 @@ h6 {
   font-weight: $heading-font-weight;
   color: $alt-fg-color;
   margin: 6.4rem 0 3.2rem 0;
+  text-align: center;
 }
 
 h1 {

assets/scss/_content.scss

@@ -7,6 +7,7 @@
     header {
       margin-top: 6.4rem;
       margin-bottom: 3.2rem;
+      text-align: center;
       h1 {
         font-size: 4.2rem;
         line-height: 4.6rem;
@@ -56,6 +57,11 @@
     font-size: 1.6rem;
     margin: 0;
   }
+  .featured-image {
+    display: block;
+    margin-left: auto;
+    margin-right: auto;
+  }
 }
 
 .avatar img {

layouts/posts/single.html

@@ -28,7 +28,7 @@
 
       <div>
         {{ if .Params.featured_image }}
-          <img src='{{ .Params.featured_image }}' alt="Featured image"/>
+          <img class="featured-image" src='{{ .Params.featured_image }}' alt="Featured image"/>
         {{ end }}
         {{ .Content }}
       </div>