Do not modify the style.css file from Divi because it will be overwritten after an update.
You need to use a child theme for that or place the ode in the Custom CSS area from theme options, that stores it into the database (options) and it's not deleted after an update.

Now, the footer has a default float of left, you need to set it on none for the footer for those to be on the center.

Please let me connect again so I can do that.

[token]Please Attach Your Support Token[/token]

Thank you in advance.