Several of the websites I frequent display text that gradually gets dimmer and dimmer until you can’t read it any more. The goal is to get you interested in a story that resides behind a paywall. If you want to read more have to join the club to log in.
This example from the Wall Street Journal shows what I mean:
Is there a stack somewhere that produces this fading text?
What kind of stack would you use to link the text to some kind of pay wall?