Fix UI-text variable and add Danish Translation for Back to top (#1598)

* Added Danish Translation for Back to top

* Update categories.html

* Update tags.html

* Update posts.html

Harmonize class names

Configure entries layout `list` or `grid`

Switch between list or grid view by adding `entries_layout` to YAML Front Matter.

Add posts, categories, category, tags, tag, and collection layouts

Replace sample pages with hard coded HTML and Liquid in favor of a layout that does all the heavy lifting. Assign the appropriate `layout` via YAML Front Matter and away you go.