Basically, you'll found assets in the directory views of the module:
- modules/your_module/views
In this directory, you'll found native CSS, JS and templates of the module.
For instance in Prestashop 1.7:
- stripe_official/views/templates/front/payment_form_card.tpl
- stripe_official/views/css/checkout.css
- stripe_official/views/js/stripeCard.js
To customize your display according to your theme you need to copy files you need to update.
For instance in Prestashop 1.7:
- /themes/your_theme/modules/stripe_official/views/templates/front/payment_form_card.tpl
- /themes/your_theme/modules/stripe_official/views/css/checkout.css
- /themes/your_theme/modules/stripe_official/views/js/stripeCard.js
When the module will charge in front-office files, PrestaShop will replace original by those from your theme.
In Prestashop 1.6:
- themes/our_theme/css/modules/stripe_official/example.css
- themes/our_theme/js/modules/stripe_official/example.js
- themes/our_theme/modules/stripe_official/views/templates/front/payment_form_card.tpl
While this path is a little different:
- themes/your_theme/css/modules/stripe_official/views/css/checkout.css
- themes/your_theme/js/modules/stripe_official/views/js/stripeCard.js
- themes/your_theme/modules/stripe_official/views/templates/front/payment_form_card.tpl