手改每一段字号，后面一改就乱。建议：正文用「正文」样式；章用「标题 1」；节用「标题 2」。需要统一改字号时，只改样式定义，全文会一起更新。目录、导航窗格也依赖这些样式。
标题 1 / 标题 2 / 正文：比手改字号更稳的做法
Heading 1 / 2 / Normal: better than resizing by hand
Hand-sizing every paragraph breaks later edits. Prefer Normal for body, Heading 1 for chapters, Heading 2 for sections. Change the style definition once to update the whole document. TOC and Navigation Pane also rely on these styles.