Because the file FormatAreaStyles.css has moved to a new location, restore your original from your backup location to %TRIDION_HOME%\web\WebUI\Editors\Base\Configuration\.
読み込んでいます...
Reinstating your logging directory for the Transport Service
Reconfiguring the Content Manager Explorer website
Backing up FormatAreaStyles.css
Configuring after the upgrade
Backing up your Safeguard configuration
Backing up TCM54.config