I have a question that can we set up page layouts/templates/themes according to tags/categories. Example will give you clear idea about this need.
e.g. Assume we have a blog on Technology. Theme background having the pictures of gadgets like mobiles,laptops etc.. And navigation bar having sections like Smartphone,Laptops,Software etc. Now when a visitor visits our blog (homepage), he/she will see a background image containing lots of gadgets. Now when he/she click on Smartphone, this action will redirect the visitor to the post list having Smartphone tag/category, But when he/she arrives on that page background image should be change to only Smartphones.
I have tried to be brief as much as I can. But if you have any doubt regarding my question, I can explain deeply.