noun
for appearances' sake; to keep up appearances
Used when something is done mainly to maintain a good outward impression, not for substance. Often adverbial with に.
体裁上、彼は賛成したふりをした。
For appearances' sake, he pretended to agree.
体裁上は謝ったが、心からではなかった。
He apologized to keep up appearances, but it wasn't sincere.