Question regarding 'Full screen background'

I’m following the official appagyver documentation for ‘Full screen backgournd’ (Full Screen Background)

I have set the PAGE LAYOUT as asked, also I removed all the paddings:

After including a new container with a background image, I tried 2 solutions to make the container full:

(1) “my” solution is setting the WIDTH and HEIGHT to Custom:Grow to width/height. And the result looks correct.

(2) setting the heigth to the formula systemVars.dimensions.viewport.height as stated in the documentation, seems that the container is now overflowing the viewport/screen size (see below):

Why is that happening ?

Often, I’ve been facing this same kind of overflowing when drawing some pages.

Best Regards.
Kleyson Rios.

Your method was recommended by an AppGyver team member:
Full page background/wallpaper - Question - AppGyver

@dwidge thanks for your answer.

But my question is not related with the problem in the other thread.

I’m new in AppGyver and I’m reading and following the documentation for learning.

Then my question in this thread is just for clarification regarding a procedure stated in the documentation that leads to a strange behaviour.

Best Regards.