The upper element moves to the lower position; changes its size (reduces in size if initially larger and enlarges if initially smaller); gets laterally inverted and its circular part changes colour (becomes black if initially white and vice-versa). The lower element moves to the upper position; changes its size (reduces in size if initially larger and enlarges if initially smaller); rotates through 180 o and its circular part changes colour (becomes black if initially white and vice-versa).
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