Get a blank line after div by simply leaving an empty line in the editor

A solution is to create a new class, say extra-space, with css margin-bottom: 0.5em and write

<div class="myclass extra-space">...text...</div>

when the div need more space.

Important: the class extra-space has to be placed AFTER the other class in the style.css file, otherwise the extra space will not be added.