letter-spacing at element boundaries

Test passes if the pattern is identical in all three blue boxes.

A A A B B B

AAA BBB

A A AB B B

AAA B B B

A A A B B B

AAA BBB

A A AB B B

AAAB B B

A A A B B B

AAA BBB

AAA B B B

A A A B B B

AAA BBB

A A AB B B

AAA B B B

A A A B B B

AAA BBB

A A AB B B

AAAB B B

A A A B B B

AAA BBB

AAA B B B

A A A B B B

AAA BBB

A A AB B B

AAA B B B

A A A B B B

AAA BBB

A A AB B B

AAAB B B

A A A B B B

AAA BBB

AAA B B B