Custom spoilers

[input type="checkbox" class="secret-checkbox" id="unique-secret-checkbox-1"] [label for="unique-secret-checkbox-1" class="secret-label"]Reveal Secret[/label]

This is the hidden secret content with potential for

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[input type="checkbox" class="secret-checkbox" id="another-unique-checkbox"] [label for="another-unique-checkbox" class="secret-label"]Show Hidden Info[/label]

More hidden information, maybe with a link: World Anvil.