Hello

I fixed it in this forum but did not create a commit and PR until now. Check your own example, a reload from the server might be necessary (push [CTRL]+[F5]). Change the following code.

style.css, line #659 (optional [1]):

/* from */
#ajax-preview-content img { max-width: 100%; }
/* to */
#ajax-preview-content img { max-width: 100%; height: auto; }

style.min.css, line #436 (mandatory [1]):

/* from */
#ajax-preview-content img{max-width:100%}
/* to */
#ajax-preview-content img{max-width:100%;height:auto}

The commit in the repository will follow.

Tschö, Auge

[1]: Assumed you use the default theme in it's default configuration.