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Glossary

What is CSS in EPUB?

Updated:

EPUB uses ordinary CSS stylesheets for presentation, but reading apps may override fonts, margins and colours, and some properties, such as fixed positioning, are unreliable or not allowed. Good EPUB CSS is short and lets the reader decide.

Why it matters when you convert a PDF to EPUB

A PDF has exact fonts, sizes and positions for every line; copying them into CSS produces an EPUB that fights the reader's settings. A converter should keep only structure-related style (headings, emphasis, block quotes, note sizes) and drop absolute sizes and positions.

How EpubCC handles it: every book gets the same short stylesheet: small side margins, a 1.45 line height, justified paragraphs with a first-line indent and automatic hyphenation, four heading sizes, centred figures and smaller notes. No font family, colour or absolute position is copied from the PDF, so the reader's own font and size settings apply.

Related terms

EPUBCheck messages about this

  • CSS-001 The "…" property must not be included in an EPUB Style Sheet.
  • CSS-006 CSS selector specifies fixed position.
  • CSS-008 An error occurred while parsing the CSS: ….
  • RSC-013 Fragment identifier is used in a reference to a stylesheet resource.
  • OPF-041 Fallback-style item with id "…" could not be found.
  • CSS-002 Empty or NULL reference found.
  • CSS-003 CSS document is encoded in UTF-16. It should be encoded in UTF-8 instead.
  • CSS-004 CSS documents must be encoded in UTF-8, detected …;
  • CSS-005 Conflicting alternate style tags found: ….
  • CSS-007 Font-face reference "…" refers to non-standard font type "…".

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FAQ

What is CSS in EPUB?

EPUB uses ordinary CSS stylesheets for presentation, but reading apps may override fonts, margins and colours, and some properties, such as fixed positioning, are unreliable or not allowed. Good EPUB CSS is short and lets the reader decide.