pandoc/test/command/5819.md

% pandoc -t revealjs --slide-level=2
# Heading

one

. . .

two
^D
<section id="heading" class="title-slide slide level1">
<h1>Heading</h1>
<p>one</p>
<div class="fragment">
<p>two</p>
</div>
</section>