Summer Sleepover Outfit Ideas?

Hi, im a short, brunette with lightly tanned skin and warm brown eyes. Im going to a sleepover tonight and since there are some girls going, who are not my friends, i really want to make a good impression. I know good friends wont judge you, but im not worried about my friends, im worried about the other girls. I really want to fit in with them, since most are very fashion forward. I need two outfits, one for today and one for tomorrow plus pjs.. Any Outfit Ideas? :)