Client area Default template customization file

[sistegraf]

Hi,

 

Would you please direct me towards what file is the one I need to modify to customize colors in the client area?

 

I'm using the "Default" template and I see 3 css files:

 

1. bootstrap.css
   
2. invoice.css
   
3. whmcs.css
   

 

I can't seem to find the way to do it, not even sure if those are the files to tweak.

 

Thanks for your help.