Hope this isn't too late. I presume you're writing to a woman -- a couple words will change otherwise.

Dlya tiyeyi, u kogo ochi syayut' yak bezkrajne kryshtalevo-golube more.
Z dnem narodzhennya, Dashinka.
Z lyubov'yu,
Tarrachka

?i??, ? ? ??i ?? ?? ?-??? ?.
? ? ?, ???i?.
? ??'?,
??

Literal translation: 'To the woman whose eyes shine like an unbounded crystal-blue sea.' And I used the word that means light blue, not dark.