That is what is so nice about having boys...lol!!
I don't post much at all, but I have a suggestion. Why not separate her school close and play cloths? Then other then shes going to get frost bite or heat stroke, don't worry to much about to warm to cold. My lovely 13 year old took along time to get that I was just trying to make sure she was comfortable. Once I finally just worried about being in the dress code and fitting correctly she got it!!! I let her wear strips and poke-a-dots and flowers all together, I let her ware long pants and long sleeves on HOT days. Now she ask about the weather and if something is going to be ok. No joke it took about a hole school year! This morning its already mid 60's and she wanted to wear a winter coat. I told her she didn't need it just a jack it and let her go. If she wore the heavy one she'll have to lug it around the afternoon. Sometimes they just life to fight with you over it, I know its dumb but they are trying to have control over things in there lives and they find one place to try and push it. Music, cloths, food and other things. let her have some control over what she wares and with some luck you won't have to fight with her anymore.
I think it is great you have standards about your girl's dress.