The look, feel, and functionality of your pages can be modified by adding custom css and JavaScript files in your page/site settings.
→ Details: Page settings
→ Details: Site settings
Customizations are your responsibility to develop, maintain, and fix
There isn’t a way for Cascade admins or template admins to be centrally aware of your customizations and, as such, those customizations can’t be accounted for as the template evolves.
Tips for creating custom css
Tips for creating custom JavaScript