Problems with custom css after updating Saffron template

Hello, I updated my template (Saffron) and all the settings of the custom css I made within the template were set to default again. It took me weeks of work to come to this point were all my settings were about right.
Of course I made a back up first so I was able to restore everyting. But what is the trick, how do you install an update without messing with the customized css?

It’s called Child Theme … make changes in Child Theme, not in Base Theme. If buyed product do not include it, You can always try to make it with plugin or … make backups.