There's nothing worng with liking girly stuff and being into STEM.

I'm a pretty "masculine" (for a lack of better expression) guy who likes a fair amount of girly stuff. My best friend is a girly girl who's in STEM and she's brilliant at her job.

If your girls want to be girly, there's nothing wrong with it! I don't understand the recent "trend" of people being against girly girls or or boyish boys. People will choose to be what best suits them. And if your girls decide they don't want to be girly at one point in their life, also great.