Title command with brown color,transforms into white

The "brown" color not works at /title

What I expected to happen was...:
The "Brown" color affect the title

What actually happened was...:
The brown color are transformed into white color

Steps to Reproduce:
1:Put /title @p title

{text:" Test",color:brown}

at a command block
2:Trigger the command block
3:See that is White,not Brown