How can I use an Opera theme on my desktop.
How to use Opera theme on desktop
Check out https://forums.opera.com/topic/15465/opera-37-is-theme-image-darkened/10. You will find themes in 2 directories. They are packaged in .zip folders; if you open the folder you will find the image file(s) which you could copy to some convenient directory, say Pictures. Once there, rt click on the file and the menu will prompt you to set it as desktop background.