Add kiosk.js file with the content below to your www folder in config.
Like any other custom script, use ui-lovelace.yaml resources section to reference the kiosk.js file.
Make sure you add kiosk somewhere in your URL. You can use it in the id of your view or in the query string.
Examples:
/lovelace/0?kiosk
views:
- title: Kiosk
icon: mdi:heart
id: kiosk_alarmIf this is your first file in www make sure you restart Home Assistant.

I'm sure you have, but just to double check, are you using a URL like my example below? Just add /kiosk to the end. Also you could create a specific userID and perhaps specify to hide the sidebar as the default? The space issue is definitely what the old code did, its covered by adding a line specified in the configuration.yaml
http://192.168.0.24:8123/lovelace/20/kiosk
Example in ui-lovelace.yaml
`
resources:
type: js
type: css
type: js
`