Easy html and css overwriting

[hellyworld]

First of all, I do not have may experiences with package modification so please be patient.

I need to integrate the app in my project and to have a functional blog page. For this i need a integrated solution but that will use my base.html and design model.

To have possibility to create a new_base.html that will change all the blog-it pages.
More details about CSS classes and how to change the design. At least to have the possibility to change the color pallet.