You can add custom CSS code into Theme Options > Theme custom CSS, or Theme Options > Additional custom CSS, or style.css file of the child theme. Such code won’t be lost after the theme update.
Don’t forget to backup all the files before any update https://xstore.helpscoutdocs.com/article/63-theme-update Also, you can make backup of Theme Options from Theme Options > Import/Export > download the export file to a safe place.
