The chat layout is based mainly on CSS styles.

The better solution would be add custom styles to override chat layout directly in the template used on your site.

Editing the main css file used by JChatSocial is possible but not recommended because on updates it will be overwrited and all custom changes will be lost.

The main CSS file used by chat component is named mainstyle.css, it's a minified file and is located under folder named 'css' following frontend component path.