As long as it looks good on them, anything is fine.
As long as the hairstyle suits the person, then I guess any kind of hairstyle is fine.
この場合、as long as「〜さえすれば・〜する限り」を使って言えます。
ーAs long as it looks good on them, anything is fine.
「その人に似合っていればなんでも良いと思う。」
look good で「似合っている」
ーAs long as the hairstyle suits the person, then I guess any kind of hairstyle is fine.
「その人に髪型が似合っていれば、どんな髪型でも良いと思う。」
suit で「似合う」
hairstyle で「髪型」
ご参考まで!