Hi,
You can style the Module's at Templatetoaster -> Module Positions. Here you can set the Background, Border, Margin and Padding for these module's.
After export, when you assign the module to these positions, make sure that you have set the style option none for these module positions. Joomla admin -> Extensions -> Template Manager -> Default template -> Style options -> your defined module position -> None -> Save.
Well, you can provide the module class suffix to the modules at Joomla backend and add the custom css for these class suffixes at TemplateToaster -> general -> Css, which will automatically get included in the template.css file.