Retain CKEditor styling
By default the text format filter "Limit HTML tags" will strip out "style" attributes in your HTML.  You can't configure this via the admin but you can replace the filter with WYSIWYG Filter and configure that to allow specific styles whilst still filtering out dangerous HTML.  The settings are found at /admin/config/content/formats/filtered_html (or replace "filtered_html" with the name of any other text format you need to alter).  See this issue for pointer as to how best to set this up.

Please note though that if you're not sure what you are doing here then you may compromise the security of your site by setting up WYSIWYG Filter in a less than ideal way.