1. No blending. Duck should be yellow everywhere.
    2. Simple blending. Duck should be a horizontal rainbow inside, and blue on overflow.
    3. Parent is a stacking context. Duck should be a horizontal rainbow inside, and yellow on overflow (since there is no background there to blend with).
    4. Intermediate parent - no stacking context. Duck should be a vertical gradient inside, and blue on overflow.
    5. Intermediate parent with grandparent stacking context. Duck should be a vertical gradient inside, and yellow on overflow.
    6. Intermediate parent has overflow. Duck should be a vertical gradient inside, and overflow is hidden.