How in the ♥♥♥♥ are spray paint decals in Half-Life so wide and large?

[aeiou [DFS]]

While playing Half-Life, I noticed a large spray paint decal and a wide one, which got me thinking about the size limit for such decals in Half-Life. I had never seen a spray paint decal that big before. So, who's willing to clarify the size limit for spray paint decals in the game?

[Ikagura]

Maybe because for convenience most decals are bigger than we thing but get the transparency effect.