城墙要「修得住」，既要补砖也要补浆，还要维持墙面的酸碱与湿度。对应配方思路：以屏障修护为核心，而非以猛药去角质或强刺激美白为先。

砖体要「饱满、规整」，才能被灰浆紧密粘合，对应甘油、泛醇、尿囊素、氨基酸、透明质酸钠等保湿舒缓成分提升角质层水合。

灰浆要「比例对、填得满」，砖墙才不漏。常用神经酰胺 NP/AP/EOP、胆固醇、硬脂酸、植物鞘氨醇。

Bricks must be plump and regular to be cemented tightly — this is the role of glycerin, panthenol, allantoin, amino acids and sodium hyaluronate.

Mortar must have the right ratio and fill completely: ceramide NP/AP/EOP, cholesterol, stearic acid and phytosphingosine.