Hi,
I will suggest CRM Themes only. But you if want you change the color other than this you can do something like this.
1. Use developer tools (F12) to change the CRM components color.Check Which crm css class is used for "setting" tab.
2. Refer below blogs to implement first step.
https://snataw.wordpress.com/2014/01/30/prettify-entity-form-in-crm-2013/
https://ashwaniashwin.wordpress.com/2014/07/18/add-color-to-the-entity-forms-header-in-the-new-crm-2013/
NOTE:
THIS IS NOT SUPPORTED APPROACH
If you find this post helpful then please "Vote as Helpful" and "Mark As Answer". Thanks and Regards, Mohammad Yusuf Ansari
http://microxrm.blogspot.in