How would i go about making a viewport frame hide parts of it that are outside of frame borders?

[Frostholl (Frost)]

I want to make a viewport frame behind this bar but i’m not really sure on how to achieve this…
this is how it looks like:

and this is how i need it to be (must not be visible after the red lines):

explorer:

Is it even possible? I’m not really experienced in working with gui objects.

(I tried tampering with frame properties like ZIndex and ClipsDescendants but didn’t really figure it out)

[Frostholl (Frost)]

Figured it out!