When Opera 7 was released, it came with a very nice default theme that was relatively refreshing, with 3D icons, and a new mail client.
It did not last long, and in Opera 7.54 the icons were replaced with flat ones.
Update: Replaced broken icons
The icons here were created based on the originals, but higher resolution, while others are from the other Opera like theme I uploaded here, Browser 7.54.
Some, like the Rewind button, did not exist originally.