In recent years many users have wished for their site to be able to have their logo centered which was simply to do with the basic themes that SE Have.
While in the world of today we have Responsive Themes meaning the layout changes per device you will never get the exact look of different devices.
The old Method of center is no longer valid
<center><img src="your url"></center>
If you go to your AP and Theme Editor and Select your theme.css
As you look through the coding you will find the code relating to the logo
All you need to do is make a slight change position:center
with doing this change you would need to make a few other small changes to the margins left and right these need to be changed to auto.
theme_content_columns_left_width: 220px; theme_content_columns_right_width: 220px;
These would need to be changed to auto as below.
theme_content_columns_left_width: auto; theme_content_columns_right_width: auto;
These two codes are only examples as yours may be different depending on the theme itself.
Also make a backup of any documents changed in-case the changes don’t work correctly you can always revert back.