In Ghost, the markdown for image is

Is there a hidden format for adding a class in the img
tag? Or is this feature not in Ghost yet?
I wanted to have a result like this:
<img src="src" alt="alt" class="img-thumbnail">
I don't want to use the html markup. I really need to achieve this using markdown. Please help..
In plain markdown classes for images are not possible. In some implementations it is possible, e.g. markdown extra uses  {.class}
.
I tried it, but in Ghost it is not possible, neither 
. Also no hints in the doku.
But you can use a workaround:
If you use the src
as css-attribute!
Just add an 'useless' hash to the URL:

Then you can address this in CSS or JavaScript:
img[src$='#img-thumbnail'] { float:left;}