(switch-to-buffer (get-buffer-create "demo"))
(buffer-face-set 'variable-pitch)

(setq words "Voluptatem est nostrum impedit nesciunt eum. Recusandae voluptatem quaerat hic harum. Consequatur in fuga nihil aliquid commodi rem sunt. Aperiam odio odio amet.")

(insert words "\n\n")
(insert "  " words "\n\n")
(insert "* " words "\n\n")
(insert "## " words "\n\n")
(insert (propertize (concat "## " words "\n")
                    'face '(:background "red" :height 300)))
(goto-char (point-min))

(setq extra-indent (pop command-line-args-left))
(when extra-indent
  (setq visual-wrap-extra-indent (string-to-number extra-indent)))

(visual-line-mode)
(visual-wrap-prefix-mode)