authors posts link view

Hello,
I don’t know why if I click on the “by author” it shows me the posts but it doesn’t include my theme format and style.
Let me show you how bat it looks:

http://romaniada.com/?author=1

It should be like this:

http://romaniada.com/?cat=23

All the posts nicely integrated with my theme

What I should do to fix this?

Thank you