Can confirm BGP’s assertion. Opened it in GIMP. At the upper-right I erased some of the picture so you can see what “Transparent background” looks like in GIMP.
You may be a trickster, Trixie, but I’m a scientist! :P
Okay, I cannot for the life of me figure out what exactly is the trick here. Obviously, if you examine the picture, you’ll notice that the sign is transparent, and therefore it takes some of the color from the site’s background. The DARK/LIGHT words are put on top of one another, and my assumption was that the light one is transparent white, therefore becoming invisible against white, and the dark one is transparent color of the dark theme, therefore becoming invisible against it.
But I have NO idea how can it still work when mixed with the color brown, OR how the DARK/LIGHT words don’t visibly overlap each other.