How to change CSS styles in the Joomly modules
For the Callback module you can find CSS styles:
“root/modules/mod_joomly_callback/css/callback_default.css”
For the Contactus:
Classic layot: “root/modules/mod_contactus/css/contactus_form.css”
Popup layout: “root/modules/mod_contactus/css/contactus_lightbox.css”