When a single paint color (we will say green) is in "lane 1" on a space pipe, it will show green when you build the landing ramp to a platform. I have seen that when an underground space pipe is used and it goes under another color (say red), the availability icon at the ramp will toggle between the two in the same way that two colors on the same lane would, despite them not actually intersecting. Hopefully this is a new bug. I don't actively follow these things! Cheers and thanks for the awesome game!
#Paint color availability glitch
kindred creek
winged walrus