You're very welcome, hope it's a great day for you.

Thank you for your lovely birthday wishes; they were greatly appreciated. :D

Just thought i'd stop by to wish you a very Happy Birthday, hope it's the best day of your life.

You're very welcome, i hope you had a great birthday.

Thank you for your birthday greetings; I appreciate that.

A very happy birthday to you, i hope it's the best one of your life.