Step 1: After opening FTP /Cpanel go to the following path (/templates/cloudx/css/)
Step 2: Now in next step you will see this file and you have, from this file just remove the _new so that the file will look like cloudx_overrides.css.
Step 3: After renaming your file name should looked like this and hence it will automatically get included on the theme similarly you can override any existing rule of css or add your own. This file will never get replace in any upcoming updates of theme.
