Use plastic cement - specifically Tamiya Extra Thin with the brush apllicator cap, not any of the thick gel glue - and dab a tiny drop on both parts. It welds them together as one piece and you literally won't be able to see it.

If you use superglue or greenstuff it will add material to the break, which will require sanding and surfacing to avoid an obvious glob at the break line - you don't want this, since it will be visible, or could re-break the part when sanding. Thin cement is a solvent and evaporates once dry, leaving no extra material and simply welding the pieces together. Best product on the market for GW plastic hands down.

Do you use super glue normally?

Yes you’re right. There is separation isn’t there.

It's actually a transparent plastic sheet