How to change background from white to black and text from black to white

My website is https://www.ce-zone.nl

Is there another option to change what I would like to have changed? Can I update the theme settings at the source pages.

I found out now, I can’t use the features of custom design if I would upgrade to a paid WP plan, since I have a selfhosted wordpress site. Is there really not any other simple way to change this format?

Custom Design is something that only applies to WordPress.com sites, it’s not applicable when you’re running WordPress on your own hosting.

Since you’re already using Jetpack, an easy way to add custom CSS is to activate the Custom CSS module. You’ll then add your custom CSS in the new stylesheet editor that’ll appear in your dashboard, under Appearance > Edit CSS.

Making the text white and the background black throughout Cubic would require some extensive CSS changes, since the colours are defined in several places.

This will get you started making the switch, but you’ll likely have to add other elements:

.site-content {
  background-color: #000;
  color: #fff;
}

Using a browser inspector will help you identify other elements to be tweaked.

Thanks for the advise and instructions.

Will edit and follow up my less complicated questions.