D:27 up staircase can exist in darkness
The D:27 staircase up (with the wall of searing flames) can exist in darkness, which is illogical.
It would be quite cool to make only the staircase visible in a dark room (if the flame wall is deep in the staircase), maybe even having the '<' red as long as the wall exists, but if it's too much for a flavour item, the room could simply be generated as never being dark.