Hot take: maybe it's better to let Haruki keep her fashion that way, she's comfortable, already popular and pretty enough without being stylish; boosting her girl power with girly clothes will just make it so that creeps will try to pick her up when she's outside.
I'm pleasantly surprised at the lack of external drama so far like love rivals and bullies, this is a pretty comfy read even including Haruki's lonely moments. Hayato is also not a spineless coward, that alone already puts him above many romcom protags.
On another note, I'm really liking the translation style they use here. Hayato and Himeko are certified country bumpkins while Haruki is a card-carrying tomboy, so the translation style really, really works well to bring that feeling across.