Hi,
Most joomla templates won't load any CSS files when tmpl=component is used. Because they think you would use this page only for printing functionality, but we are using it to generate the QuickView page.
You can force to load what ever CSS file you need inside the iframe modal popup.
Open this file:
/templates/YOUR_TEMPLATE/component.php
and manually include what ever CSS file you want to load inside the iframe modal popup (with an ordinary HTML lines, right before the closing </head> tag)
Regards,
Support