Hi,
you can do this with a simple CSS code like this

.jsn-l-map .jsn-l-avatar img{

    width:20%;

}

Hi,
this is not something so simple because width of infowindow come from Google Map.

the only way (not tested by us) is to override module template and add code to set a max width, see here https://stackoverflow.com/questions/3844314/controlling-the-width-of-a-google-maps-infowindow

To override module template you can follow these steps:
- Copy file from modules/mod_jsnmap/tmpl/default.php to /templates/your-template-folder/html/mod_jsnmap/default.php
- edit new file

Oké that's an option, but I think it's also an option to use px instead of %.
In that way the panel has collapsed automatically and gets an acceptable format.

This code helped me to fix this issue.

.jsn-l-map .jsn-l-avatar img{
width: 50px !important;
height: 41px !important;
margin-bottom: 8px;
}

But thanks for your awesome support!
We appreciate that.

Kind regards,
Lumiga