remove widgetback.png for login button

Hello, thanks for this theme, i love it 🙂

i managed to custom a bit this theme like i want (i’m using it for a minecraft server ^^)

but i would like to change a thing and don’t know where to find it

this button is using the same image than widget menu, but i like to change it only for this button, or remove it ? is it possible ?

thanks for help