Restructure & refactor codebase

internal/glance/templates/page-content.html

@@ -0,0 +1,13 @@
+{{ if .Page.ShowMobileHeader }}
+<div class="mobile-reachability-header">{{ .Page.Title }}</div>
+{{ end }}
+
+<div class="page-columns">
+{{ range .Page.Columns }}
+    <div class="page-column page-column-{{ .Size }}">
+        {{ range .Widgets }}
+            {{ .Render }}
+        {{ end }}
+    </div>
+{{ end }}
+</div>