Thanks for the nice feedback.
Level 5 shouldn't have that line, but by the time I realized it, it was too late. To facilitate navigation, you can zoom in and zoom out.
I only tested it in Chrome, so it was to be expected that it would cause problems in other browsers...
I was aware of this bug in the failure message, but I thought I had fixed it.
I'll make these corrections and some improvements later... Thanks for playing!