Change the css style

I would like to change the style of the tabs of my registering pages and details pages but i don´t know how to change them. I see that they use a class that is called cbTabNav. I try to override it in the template but it doesn´t override the default value. how can i change them properly?in the component? Defining something? it is just the style, intead of the blue color I would like to use another color for these tabs.

They're styled entirely by Bootstrap 3 (this is currently being updated to Bootstrap 4). Any Bootstrap 3 compatible Joomla template should style them fine. If you don't have such a template then read up on Bootstrap 3 documentation and write whatever CSS is necessary to style them how you want. You maybe able to use a Bootstrap 3 theme generator as well I suppose.