An EPUB page break should be an explicit structural decision at a chapter or scene boundary, not a stack of blank lines that happens to push text onto another screen.
When working on EPUB page break, consider a two-chapter essay whose second chapter must begin on a new screen. The task is complete only when placement outside ordinary paragraph text and absence of unintended blank screens can both be confirmed after the saved output is reopened. An export message by itself does not answer the search question.
Decide what success means for this book
For this example—a two-chapter essay whose second chapter must begin on a new screen—the first decision is whether placement outside ordinary paragraph text has a known starting value. The final decision is whether absence of unintended blank screens survives export and reopening. Keeping those two moments separate prevents a temporary editor display from becoming the handoff criterion.
Preserve the received manuscript, edit an editing copy, and write the EPUB separately. With EPUB page break as the goal, those three files keep the source, intentional edits, and packaged book distinct.
The direction is one-way: preserved source, editable duplicate, separately written EPUB, then a reopened EPUB. The method does not recreate the manuscript from the EPUB or treat the package as an editing source.
Build a representative test case
Build the example around a two-chapter essay whose second chapter must begin on a new screen. Keep the part that could genuinely fail. If the risk concerns separation from visual paragraph spacing, include the exact chapter, character, path, or label that creates that risk. Removing it for a cleaner demo would produce an easy pass with no value for the real book.
Examine four independent facts
- Placement outside ordinary paragraph text: while you mark intentional new-page boundaries, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from separation from visual paragraph spacing.
- Separation from visual paragraph spacing: while you remove accumulated blank lines, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from the emitted page-break rule in XHTML or CSS.
- The emitted page-break rule in XHTML or CSS: while you insert one supported page-break marker, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from absence of unintended blank screens.
- Absence of unintended blank screens: while you export and examine the relevant XHTML, write down the expected state and what the book actually shows. Treat this as its own decision; do not infer it from placement outside ordinary paragraph text.
Complete the operation in order
- Mark intentional new-page boundaries. Before moving on, confirm placement outside ordinary paragraph text; if it differs from the expected state, correct that step rather than compensating later.
- Remove accumulated blank lines. Before moving on, confirm separation from visual paragraph spacing; if it differs from the expected state, correct that step rather than compensating later.
- Insert one supported page-break marker. Before moving on, confirm the emitted page-break rule in XHTML or CSS; if it differs from the expected state, correct that step rather than compensating later.
- Export and examine the relevant XHTML. Before moving on, confirm absence of unintended blank screens; if it differs from the expected state, correct that step rather than compensating later.
- Retest after changing reader font size. Before moving on, confirm placement outside ordinary paragraph text; if it differs from the expected state, correct that step rather than compensating later.
Walk the example from source to handoff
During step 1, mark intentional new-page boundaries. In the case of a two-chapter essay whose second chapter must begin on a new screen, examine placement outside ordinary paragraph text before changing anything else. This prevents using many blank lines as layout. If the observation is unknown, repeat that step with the editing copy instead of editing the master manuscript.
During step 2, remove accumulated blank lines. In the case of a two-chapter essay whose second chapter must begin on a new screen, examine separation from visual paragraph spacing before changing anything else. This prevents placing the marker inside a paragraph. If the observation is unknown, repeat that step with the editing copy instead of editing the master manuscript.
During step 3, insert one supported page-break marker. In the case of a two-chapter essay whose second chapter must begin on a new screen, examine the emitted page-break rule in XHTML or CSS before changing anything else. This prevents accepting one temporary reader position as proof. If the observation is unknown, repeat that step with the editing copy instead of editing the master manuscript.
During step 4, export and examine the relevant XHTML. In the case of a two-chapter essay whose second chapter must begin on a new screen, examine absence of unintended blank screens before changing anything else. This prevents using many blank lines as layout. If the observation is unknown, repeat that step with the editing copy instead of editing the master manuscript.
During step 5, retest after changing reader font size. In the case of a two-chapter essay whose second chapter must begin on a new screen, examine placement outside ordinary paragraph text before changing anything else. This prevents placing the marker inside a paragraph. If the observation is unknown, repeat that step with the editing copy instead of editing the master manuscript.
What the example showed
The trial produced this observation: The test book exported 3 chapters with writingMode=horizontal and version 1.9. Inspection returned spine=7, images=1, missing=0, nav=true, NCX=true, and valid=true.
That value belongs to the files and settings used for this example. It supports the documented sequence; it does not turn EPUB page break into a promise for every manuscript, reading system, or retailer.
The untested boundary is equally important: valid=true is a local package outcome, not retailer acceptance or identical rendering in every reader. Outside this scope: Complete Markdown conformance and identical rendering in every reader are outside scope. Add retailer preview, device testing, accessibility review, or rights clearance when the book requires those decisions.
The W3C EPUB 3.3 specification defines the EPUB navigation document as a required publication component.
Recover from the three likely mistakes
- Using many blank lines as layout: go back to “mark intentional new-page boundaries,” then re-examine placement outside ordinary paragraph text. Change only the responsible input so the next comparison remains meaningful.
- Placing the marker inside a paragraph: go back to “remove accumulated blank lines,” then re-examine separation from visual paragraph spacing. Change only the responsible input so the next comparison remains meaningful.
- Accepting one temporary reader position as proof: go back to “insert one supported page-break marker,” then re-examine the emitted page-break rule in XHTML or CSS. Change only the responsible input so the next comparison remains meaningful.
Decide whether Rune Studio fits
Rune Studio is a candidate when an editor wants manuscript work and EPUB preparation in one Mac application for a project involving a two-chapter essay whose second chapter must begin on a new screen. Product documentation describes available functions; the observation above documents only this example.
See the product on the Rune Studio website. Keep the adoption boundary explicit: complete Markdown conformance and identical rendering in every reader are outside scope.
Take the next step
Start with this action: mark intentional new-page boundaries. Then follow the remaining steps until absence of unintended blank screens can be reproduced from the reopened publication. That is the practical finish line when working on EPUB page break.