Example page (never mind the contents): https://www.klimafakten.de/behauptungen/behauptung-aber-am-suedpol-nimmt-die-eismasse-zu. Check the buttons “Kurz” (stands for short) and “Ausführlich” (stands for detailed).
Depending on which button is pressed, a different length, different detailed page is being load.
That’s something I very much would like to use for Whonix wiki. A short button for most visitors with easy, basic information. And an alternative detailed, more verbose view.
Does somehow know the required html code?
Yes, we can safely [admins only] using raw html code in Whonix wiki. (We are using mediawiki extension Widgets for that.) Example on how html is being used in Whonix wiki: