Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:3/4
K:D
['', 'f2 a>f g/f/e/d/ B2', 'cB A>B', '']  
X:1
L:1/8
M:3/4
K:D
 d>e |: f2 a>f g/f/e/d/ | B2 d>d cB | A>B dA a>f |[M:2/4] e2 d>e |[M:3/4] f2 a>f g/f/e/d/ | 
 B2 d>d cB | A>B dA f>e |1[M:2/4] d2 d>e :|2[M:2/4] d2 e>d ||[M:3/4] ce A2 a>g | f d2 ed | 
[M:2/4] ce dB | A2 d>e ||[M:3/4] f2 a>f g/f/e/d/ | B2 d>d cB | A>B dA a>f |[M:2/4] e2 d>e | 
[M:3/4] f2 a>f g/f/e/d/ | B2 d>d cB | A>B dA f>e | d4 ||  