Hello,

I can see that you found out how to fix your styling, at least for the time being

Any content that opens in a modal in Joomla needs to be styled at the template level. In each template, index.php is the page used for any page on a website, component.php is the page used for 'lone' content, content that is shown without the template framework, like in modals.

Then, when you want to style a Trombinoscope Contact inside a modal, the particular settings are the ones you can find in the global configuration of the extension, particularly in the layout and theming tabs.