Kart theme gives you an easy way to add custom CSS styles that override theme default styles. This feature is designed to meet the needs of administrators who would like to add their own CSS to their Drupal website.
How to add custom CSS
Custom CSS can be added from theme settings page.
Home > Administration > Appearance > Appearance settings > Kart
example.com/admin/appearance/settings/kart
Enable custom css option and enter your custom css codes.
You will need to clear the Drupal cache for the changes to take effect.
Navigate to: Administration > Configuration > Performance and click on Clear all caches.
example.com/admin/config/development/performance
Additional CSS File
This feature is available in KartPro theme.
This feature allows you to add an additional custom css file to the theme.