Exercise 1: An Unrecognized Color Name Falls Back Correctly — Possible Solution
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THE TEST
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    parse_color('cornflowerblue')

RESULT
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    (0, 0, 0)   -- black, DEFAULT_COLOR's own value

'cornflowerblue' is a genuine, real CSS3 named color -- it isn't a
typo or an invalid string -- but it simply isn't one of the handful of
entries this chapter's own simplified NAMED_COLORS table defines.

WHY THE FALLBACK WORKS
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parse_color's own entire body is:

    def parse_color(name):
        return NAMED_COLORS.get(name, DEFAULT_COLOR)

dict.get(key, default) returns NAMED_COLORS[name] if that exact key
exists, and the supplied DEFAULT_COLOR otherwise -- it never raises
KeyError. Since 'cornflowerblue' isn't a key in NAMED_COLORS, the
lookup falls through to DEFAULT_COLOR, (0, 0, 0).

WHY A HAND-BUILT TABLE CAN NEVER COVER EVERY CSS COLOR NAME
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The CSS Color Module defines 140+ named colors -- everything from
common ones like 'red' and 'blue' to genuinely obscure ones like
'papayawhip', 'mediumspringgreen', and 'rebeccapurple'. This course's
own NAMED_COLORS table only lists the handful of colors actually used
across this course's own examples and exercises (red, blue, green,
navy, purple, yellow, white, black, orange) -- a deliberate, honest
simplification, not an attempt to be exhaustive. Enumerating all 140+
by hand would be real, tedious work that adds nothing pedagogically
to what this chapter is actually teaching (bounds-checked rasterizing),
so the table stays small and the fallback handles everything it
doesn't cover.

WHY THIS WORKS AS AN ANSWER
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This mirrors Chapter 6's own DEFAULT_CHAR_WIDTH_EM fallback for an
unlisted character, and real browsers themselves: an actual browser
handed a genuinely invalid or unsupported color value doesn't crash
the whole render -- it substitutes a defined fallback (in real CSS,
this is formally the property's own initial value) and keeps going.
Falling back to black specifically is a reasonable, visible default --
it's clearly distinguishable on a typical white canvas background,
making an unrecognized color's own presence obvious rather than
silently invisible (which a fallback to white, for instance, would
risk being on this chapter's own default white canvas).