1920x1080
Works with all under widescreens

Please note:
With admin mode entered
copy the extracted proStyle folder into /usr/share/slim/themes then,
change theme name on /etc/slim.conf (open with leafpad)
You can locate almost on the end the current theme name... change for proStyle
Save the file...

You can put any backgrounds with blur effect
https://blur-photo.com/blur-editor

For better visual results its better to set the normal background as desktop background.