Fix: missing semantic css classes and html elements (#1583)

Fix: missing semantic css classes and html elements (#1583)

* Fix: missing semantic css classes and html elements.

Now all pages have a main and aside element when a sidebar is present to facilitate custom theming. This does not impact the default behavior of the front.

* Fix: re-added communityref on main element

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Co-authored-by: 0xAnansi <0xAnansi@omageni.com>
Co-authored-by: Jay Sitter <jsit@users.noreply.github.com>
Co-authored-by: Dessalines <dessalines@users.noreply.github.com>