Challenge 1: Moving the Text Layer Below the Background — Solution Walkthrough

What would happen:

The text would become completely hidden, covered entirely by the
background layer, since the background would now be stacked above it.

Why, per this chapter's own material:

Layer order directly determines visibility — whatever sits higher in
the stack visually covers whatever sits below it, exactly like
physical transparent sheets stacked on top of each other. If the
background layer is opaque (not partially transparent), moving the
text layer beneath it means the background now sits between the
viewer and the text, blocking it from view entirely, the same way a
solid sheet placed on top of a written page would hide the writing
underneath it.

What would need to be true for the text to remain partly visible:

Only if the background layer had reduced opacity or contained
transparent areas (per this chapter's own opacity material) would any
part of the text underneath still show through — with a fully opaque
background layer on top, the text layer would be entirely obscured.

WHY THIS WORKS AS AN ANSWER
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This exercise is a direct, practical application of this chapter's own
stacking-order rule to a concrete three-layer scenario, correctly
predicting the visual outcome of reordering the stack.