先锁定交付比例，再设计主体的安全区域。竖屏需要更强调垂直动作和近距离关系，宽画幅适合并置人物与环境；拍摄时给裁切和字幕留出边界。 Lock the delivery ratio before composing. Vertical frames favor vertical action and intimate relationships; wide frames support people in environments. Leave safe margins for crops and captions during capture.