Quick how to, make gradient_thread thinner

[aceofspades]

Im making my own forum skin at the moment. I have come across one problem though. I want to have my gradient_thread thinner than normal, however then i use a thinner gradient image it just shows the image and the background for any excess space to make up the height of the original gradient.

Can someone please tell me how to allow my gradient_thread to be thinner. See my attached image for more info (white is my gradient image and blue is the background in this case.)

Thanks,

James