Inner Border on Textarea (Quick Reply and Reply)

[sebaot]

I've been customizing things for my forum, but I can't find where to customize this inner border on the textarea where you type in a message. You can set the textarea border to 1 pixel, but it doesn't change this inner padded wall. I can't find it in any style. I'm including a screenshot of this. Does anybody know where I can remove that padded border? Or at least change the color of it. When I go with a dark forum, it stays the same color as in the attached screenshot.

Thanks in advance!

EDIT: I'm using VB 3.7.0