It’s not entirely clear, but from what I can figure out, when people cross the blue line, they pass into another strata where they become very small. The best part of this page is that the blue line itself – a sort of design guideline that floats above the art and acts as a boundary. A series of artificial panels in the middle of the bottom tier.

(Heavy Metal issue #162, May 1996 – Page 21 Stratum by Azpiri)