Right radical
页 (head/page) is the simplified form of
頁, which depicted a person's head with prominent face-features — used in body-part chars relating to the head. Anchors
顶 firmly as 'the top of the head', and by extension 'the top of anything'. Same
页 radical in
颈 (neck),
额 (forehead),
颜 (face) — all head-region body parts.