Challenge 2: Adjusting the Icon's Fill Color After Step 4 Is Already Done — Solution Walkthrough

The answer:

This request is straightforward because Step 4 applies the fill,
stroke, and layered depth effect through Illustrator's Appearance
panel (or Inkscape's equivalent Fill and Stroke properties on the
layered duplicate), per Chapter 5's own material — appearance
properties that remain live and independently adjustable on the
combined icon shape, not baked permanently into the artwork.

Why this specific step made the request easy:

Per Chapter 5, fill and stroke are properties applied to a shape, not
a destructive transformation of the shape's own underlying paths.
Changing the fill color simply means selecting the shape and updating
its fill value directly — the icon's own combined outline from Step 3
is completely unaffected by this change.

Why this contrasts with a genuinely harder request:

If the client instead asked to change the icon's actual silhouette —
its shape, not its color — that would touch Step 3's own destructive
Pathfinder result, which per Chapter 6's own warning box would require
working from the duplicated original shapes kept aside during that
step, a meaningfully bigger request than a simple fill-color change.

WHY THIS WORKS AS AN ANSWER
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This exercise checks that a fill-color change is correctly recognized
as touching Step 4's own live, adjustable appearance properties,
rather than Step 3's own destructive shape-combination result.