What I did was I screenshotted the page, cropped the canvas, then took my background image in GIMP and dragged it around until it looked good.
Totally faked attachment so you can see how I did it:
.txt (817.4 KB)
(It’s actually a XCF file, the
.pdn for GIMP. Just rename the extension - it crashed
The screenshot is on the layer “Cover layer”. I set a
background-color in Chrome before taking the screenshot, then on pasting into GIMP, I added an alpha channel, then magic-selected the green background and Deleted it.
Then, I inserted the wallpaper on a new layer below “Cover layer”, and dragged it around until it looked good. Then I made the “Cover layer” invisible and Ctrl-Exported it as PNG, and used that as my background.