How to align element in the page/post center if using Sidebar.

I was customizing gp theme and tried to add herader elements in posts, and I want to use Sidebar. But, it doesn’t align in center of the page, but above the post.

I want it to be in the center, so i Have used CSS to manage it, but it makes problem in different devices.

In some devices, the text goes front and in some back.
I have used em for the values to push it, I’m not got at CSS

The page I need help with: [log in to see the link]