EPUBFILEDesign for a page that can change
A print page has a fixed trim size. A reflowable ebook does not: readers can change screen size, orientation, typeface, font size, margins, and sometimes line spacing. That means a layout that looks perfect in one screenshot can become uncomfortable or break when a reader adjusts it.
The goal is not to make every device display identical pages. It is to keep the reading experience clear and resilient when the page reflows.
Use type with a clear job
Body text should be comfortable for long reading. A book serif can feel familiar, while a neutral sans serif can suit nonfiction or interface-like material; neither category is automatically more readable for every reader. Use a small number of type styles and make headings, body text, quotations, and captions distinct through hierarchy rather than decoration.
Embedded fonts can support a deliberate visual voice, but they add file weight and may be overridden by reading systems or reader settings. If a custom font is essential, test its embedding and fallback behavior, and make sure the book still reads well when the font is unavailable.
Keep CSS flexible
- Use relative units such as
emor%for type and spacing where appropriate, instead of assuming one fixed screen size. - Avoid forcing a small font size or preventing readers from enlarging the text.
- Keep line lengths comfortable through the reading system's natural margins; avoid fixed-width text columns.
- Use paragraph indentation or paragraph spacing consistently. Large indents and large blank gaps together can make prose feel fragmented.
- Keep line height open enough to follow, but do not set it so loose that each line feels disconnected.
Preview a range, not one perfect setting
Start with a sensible default, then preview the same passage at a smaller and larger text size, at tighter and looser line spacing, and in both light and dark reading themes. Check headings, dialogue, italics, long words, and paragraphs with several lines. A short sample can hide problems that show up in a full chapter.
A browser preview is a design aid, not a substitute for testing the EPUB in actual reading apps. Export the book and check it on at least one phone-sized screen and one larger display if you can.
