Skeleton cant use the version fallback of the CSS CDN,
because of e changed file structure and therefore needs
a specific version constraint.

Add CDN links to several more minimal CSS frameworks.

Overwrite the doucment title & header

Use one of the preselected stylesheets (eg. »skeleton«) or
the URL to any other existing stylesheet (eg. »/styles.css«).

Overwrite document content

Add the main object to get the template file