Right side
白 supplies the sound — bái → pò, drifting through the Old Chinese b/p alternation that links many
白-phonetic characters. Faint semantic hint: amber's translucent honey-gold can shade toward pale or milky. Most often seen in
琥珀 (hǔpò, amber). Same phonetic in
拍 clap,
怕 fear,
伯 uncle,
泊 moor,
帕 handkerchief.