Took a second to realize why I couldn't place lines after clicking around a bit but eventually saw the resource in top right. Neat concept, I think it could be expanded into a nice little puzzle game with some tweaks and an extra mechanic or two. The levels with tighter constraints were more interesting because it made me think more about how close I could cut the corners. A preview line and some tighter bounding boxes would've helped smooth out the trial and error. Some way of the game counting your total distance used and/or minimum lines per level would be nice too.
I enjoyed it, thanks for sharing!