Change background color from BLUE to White for Web dynpro ABAP page

Hello Experts,

I have developed a web dypro application using SAP ABAP. Now client wants to change the feel & look of UI elements such has chang background color from blue to white, look of table & introduce dynamically color like red, blue, yellow & green for specific column or column of a row. I have gone through many link before posting but not able to find a suitable one. Many link say we can not perform such changes and other say about themes. If we have to use themes then how we can do so?

Thanks

Faiz Khan