creating custom css style for the registration fields

hi! is it possible to put those fields inside a modal or when the user click register there will be a pop up box and inside that box are those fields? coz im trying to edit the css of those fields and nothing happens. i just dont feel how my registration fields looks. its very simple. and on CRF option i checked “match my theme” but it doesn’t match my theme.

https://www.ads-software.com/plugins/custom-registration-form-builder-with-submission-manager/