Tile background isn't transparent

Bugs
1

I was loading my map into pygame with pytmx, and then this bridge suddenly has a background!

image
image603×597 134 KB

In the map editor:image
so why is it greyish-green?

2

When you created the tileset with the bridge, did you need to set a transparency colour? Perhaps you haven’t done the equivalent in Pygame, causing the background colour to appear in-game.