How do I change how far a light_spot goes "down"?

[Sheeplie]

I've got a light_spot here, but, a common problem: Hammer shows the beam going down and through the floor brush. This is generally just annoying, even if it doesn't show in game. I was wondering which keyvalue changed the distance of how far the light goes down from the light_spot entity. I've tried tweaking the maximum distance value, but the light helper preview doesn't change.