What should I give my favorite female colleague for her birthday?

Since you don't know what she thinks, and you are afraid that it will be inconvenient to work in the future, I suggest buying something casual and beautifully packaged. It seems unintentional, but it still shows that you are more careful and will think of giving her a birthday present.

I think we just need to make her feel a little warm now.

Flowers are inappropriate and too ostentatious; Cosmetics are more personalized; I suggest buying chocolate, imported and expensive. Not too big, small box, it is better to pack it yourself.

Hee hee, if she likes you too, she will see it.

This is just my suggestion.

By the way, don't buy anything too fancy at first, it will make her think that you are good at pleasing girls.