How to Fix Electronic Publishing File Errors

Common Electronic Publishing File Formats

Before diving into specific errors, it's helpful to understand the major electronic publishing file formats and their characteristics:

EPUB (Electronic Publication)

The industry standard open format maintained by the International Digital Publishing Forum (IDPF):

• EPUB 2.0 - An older standard with wide compatibility but fewer features
• EPUB 3.0/3.1/3.2 - Modern standards with support for advanced features like multimedia, interactivity, and accessibility
• Structure: Essentially a ZIP archive containing XHTML, CSS, images, and metadata files organized according to specific standards
• Used by: Most e-readers except Kindle, including Apple Books, Kobo, Nook, and Google Play Books

Kindle Formats

Amazon's proprietary e-book formats:

• MOBI (Mobipocket) - Amazon's older format, based on the open Mobipocket standard
• AZW/AZW3 - Amazon's proprietary formats based on MOBI with additional features and DRM
• KF8 (Kindle Format 8) - Amazon's enhanced format with HTML5 and CSS3 support
• Used by: Amazon Kindle devices and apps exclusively

PDF (Portable Document Format)

Adobe's fixed-layout document format:

• Structure: Contains exact page layouts with precise positioning of text and graphics
• Limitations: Not designed for reflowable content or adaptive viewing on different screen sizes
• Used for: Documents where layout precision is critical, academic papers, print-replica e-books

Other Formats

• iBooks (.ibooks) - Apple's proprietary format built on EPUB with additional features
• CBZ/CBR - Comic Book ZIP/RAR, used for digital comics and graphic novels
• DJVU - Specialized format for scanned documents and books with high compression
• FB2 (FictionBook) - XML-based e-book format popular in Eastern Europe

With this foundation, let's explore common errors in electronic publishing files and their solutions.

EPUB File Errors and Solutions

EPUB files are essentially ZIP archives with a specific structure of HTML, CSS, and metadata files. This complexity creates numerous opportunities for errors.

Error: "Cannot Open Book" or "Invalid EPUB Structure"

Causes:

• Corrupted ZIP container structure
• Missing or incorrect mimetype file (must be first in the archive and uncompressed)
• Missing META-INF/container.xml file
• Invalid or missing OPF (Open Packaging Format) file
• Incomplete download or file transfer

Solutions:

1. Validate the EPUB structure:

   Use validation tools to identify specific structural problems:

   • IDPF EPUB Validator (online)
   • EPUBCheck (command-line tool): java -jar epubcheck.jar your-book.epub
   • Sigil's built-in validation (free EPUB editor)
2. Repair the ZIP container:

   Rename the .epub file to .zip, extract the contents, then recreate the ZIP file with proper settings:

   cd extracted_folder
   echo -n "application/epub+zip" > mimetype
   zip -X0 ../fixed.zip mimetype
   zip -Xr9D ../fixed.zip * -x mimetype
   mv ../fixed.zip ../fixed.epub

   This ensures the mimetype file is uncompressed and first in the archive, as required by the EPUB specification.

3. Check file references:

   Extract the EPUB and verify that all files referenced in the OPF and HTML files actually exist. Common issues include:

   • Missing image files referenced in the content
   • Case sensitivity issues in file paths (important since many e-readers run on Unix-like systems)
   • Incorrect paths in the OPF manifest
4. Rebuild with an EPUB editor:

   If validation reveals multiple issues, consider opening and saving the file with a dedicated EPUB editor:

   • Sigil (cross-platform)
   • Calibre (cross-platform)
   • Adobe InDesign (commercial)

Error: "XML Parsing Error" or "Invalid Content Document"

Causes:

• Malformed XML/XHTML in content files
• Unclosed HTML tags or improperly nested elements
• Invalid character entities or special characters
• Non-UTF-8 encoded text without proper declarations

Solutions:

1. Locate and fix specific XML errors:

   Use the line and column numbers from the error message to locate problems in the content:

   • Check for unmatched opening/closing tags (<p> without </p>)
   • Fix improper nesting (e.g., <em><strong>text</em></strong> should be <em><strong>text</strong></em>)
   • Ensure all attributes have quoted values
2. Validate XHTML content files individually:

   Use online validators like the W3C Markup Validation Service to check extracted content files.

3. Fix character encoding issues:

   Ensure all content files have proper encoding declarations:

   <?xml version="1.0" encoding="utf-8"?>

   Convert non-UTF-8 text to UTF-8 using a text editor with encoding conversion features.

4. Replace problematic characters:

   Common problematic characters include:

   • Replace ampersands (&) with &
   • Replace less-than signs (<) with <
   • Replace greater-than signs (>) with >
   • Replace non-breaking spaces with  

Error: "Missing Required Metadata" or "Invalid OPF File"

Causes:

• Missing required Dublin Core metadata elements (title, language, identifier)
• Incorrect metadata format or missing namespaces
• Invalid OPF file structure
• Missing or incorrectly referenced NCX or navigation document

Solutions:

1. Add required metadata to content.opf:

   Ensure the metadata section contains all required elements:

   <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
       <dc:title>Book Title</dc:title>
       <dc:language>en</dc:language>
       <dc:identifier id="uuid_id">urn:uuid:12345678-1234-1234-1234-123456789012</dc:identifier>
       <meta property="dcterms:modified">2023-08-09T12:00:00Z</meta>
   </metadata>

2. Generate a valid UUID:

   For EPUB 3, each book requires a unique identifier. Generate a UUID (Universally Unique Identifier) using online tools or commands:

   python -c 'import uuid; print(uuid.uuid4())'

3. Fix package document structure:

   Ensure the OPF file follows the required structure:

   • package element with proper version attribute (2.0 or 3.0)
   • metadata section with required elements
   • manifest listing all content files
   • spine defining reading order
   • guide (EPUB 2) or landmarks (EPUB 3) for navigation
4. Regenerate navigation document:

   For EPUB 2, recreate the toc.ncx file. For EPUB 3, ensure a proper nav.xhtml file exists:

   <nav epub:type="toc" id="toc">
       <h1>Table of Contents</h1>
       <ol>
           <li><a href="chapter1.xhtml">Chapter 1</a></li>
           <li><a href="chapter2.xhtml">Chapter 2</a></li>
       </ol>
   </nav>

Error: CSS and Formatting Issues

Causes:

• CSS properties not supported by all e-readers
• Inconsistent CSS interpretation across devices
• Overriding of publisher CSS by reader preferences
• Complex layouts incompatible with reflowable format

Solutions:

1. Use e-reader-friendly CSS:

   Stick to widely supported CSS properties and provide fallbacks:

   /* Instead of this */
   p {
       column-count: 2;
   }
   
   /* Use this */
   p {
       /* Basic styling all readers support */
       margin: 1em 0;
   }

2. Test on multiple devices and simulators:

   Preview your EPUB on different devices or use simulator tools:

   • Kindle Previewer (for Amazon formats)
   • Adobe Digital Editions
   • Apple Books (for macOS/iOS)
   • Thorium Reader (open-source)
3. Simplify complex layouts:

   For reflowable e-books, avoid absolute positioning, floating elements, and multi-column layouts that may render poorly across different screen sizes.

4. Use media queries for device-specific styling:

   @media amzn-kf8 {
       /* Kindle-specific styles */
   }
   
   @media amzn-mobi {
       /* Older Kindle styles */
   }
   
   @media (min-width: 768px) {
       /* Styles for larger screens */
   }

Kindle Format Issues (MOBI, AZW, KF8)

Amazon's Kindle formats have their own set of specific challenges due to their proprietary nature and differences from standard EPUB.

Error: "Unable to Open" or "Document Contains Errors"

Causes:

• Corrupted MOBI/AZW file structure
• Conversion errors from other formats
• Incomplete download
• Incompatible Kindle format version for older devices

Solutions:

1. Reconvert from source:

   If you have the original source file (EPUB, HTML, DOCX), reconvert it to the appropriate Kindle format:

   calibre-ebook source.epub --output-profile kindle --output-format mobi

   Or use Amazon's Kindle Create or Kindle Previewer tools for conversion.

2. Check device compatibility:

   Newer KF8 files may not work on older Kindle devices. Generate both MOBI and KF8 formats:

   kindlegen book.epub -c2 -verbose

   This creates a dual-format file compatible with both older and newer devices.

3. Use Kindle-specific tools:

   Amazon provides free tools to validate and fix Kindle format issues:

   • Kindle Previewer - Tests and previews how books will appear on different Kindle devices
   • Kindle Create - Amazon's official e-book creation and formatting tool
4. Examine with MOBI inspection tools:

   For advanced users, inspect MOBI files with specialized tools:

   mobi_unpack your-book.mobi

   This extracts components for examination and manual repair.

Error: Missing or Broken Table of Contents

Causes:

• Missing or improperly structured NCX file
• HTML TOC not properly identified
• Conversion process didn't preserve TOC structure
• Incorrect bookmark/anchor link structure

Solutions:

1. Create a proper HTML TOC:

   Kindle formats use both an NCX file (for the Kindle's "Go to" menu) and an HTML TOC (as a navigable page):

   <!-- In your HTML TOC file -->
   <div id="toc">
       <h1>Table of Contents</h1>
       <ol>
           <li><a href="chapter1.html#chapter1">Chapter 1</a></li>
           <li><a href="chapter2.html#chapter2">Chapter 2</a></li>
       </ol>
   </div>

2. Use proper anchor points:

   Ensure each chapter has an anchor ID that matches your TOC links:

   <h1 id="chapter1">Chapter 1</h1>

3. Convert with TOC options:

   When converting to Kindle formats, specify TOC options:

   calibre-ebook source.epub --output-format mobi --toc-title "Table of Contents" --level1-toc "//h:h1" --level2-toc "//h:h2"

4. Use Kindle Previewer to verify navigation:

   Always test navigation in Kindle Previewer before publishing, as it accurately simulates how real devices will handle your TOC.

Error: Images Not Displaying or Displaying Incorrectly

Causes:

• Images too large (dimensions or file size)
• Unsupported image formats
• Incorrect image references in HTML
• Images lacking alt text (required for accessibility)

Solutions:

1. Optimize images for Kindle:

   Format and size guidelines:

   • Use JPEG for photographs (quality 60-80%)
   • Use PNG for line art and text-heavy images
   • Keep dimensions under 2500 pixels on the longest side
   • Keep file sizes under 5MB per image
2. Batch process images:

   mogrify -resize "2000x2000>" -quality 80 *.jpg

   This resizes all JPEG images to fit within 2000x2000 pixels while maintaining aspect ratio.

3. Use relative sizing in HTML:

   <img src="images/figure1.jpg" alt="Description of figure" style="width: 100%; max-width: 600px;" />

   This makes images responsive to different screen sizes.

4. Check image paths case-sensitivity:

   Kindle devices treat file paths as case-sensitive. Ensure image references in HTML match the actual file names exactly:

   • Correct: <img src="Images/Figure1.jpg"> (if the actual path is "Images/Figure1.jpg")
   • Incorrect: <img src="images/figure1.jpg"> (if the actual path differs in case)

Fixed-Layout E-book Problems

Fixed-layout e-books (used for illustrated children's books, comics, and graphic-heavy publications) present unique challenges due to their non-reflowable nature.

Error: "Fixed-Layout Not Supported" or Display Issues

Causes:

• Device or app doesn't support fixed-layout format
• Incorrect metadata for fixed-layout specification
• Viewport dimensions improperly set
• Orientation-specific layouts not properly defined

Solutions:

1. Add proper fixed-layout metadata:

   For EPUB3:

   <!-- In the OPF file -->
   <meta property="rendition:layout">pre-paginated</meta>
   <meta property="rendition:orientation">portrait</meta>
   <meta property="rendition:spread">none</meta>

   For Kindle:

   <meta name="fixed-layout" content="true"/>
   <meta name="original-resolution" content="1600x2560"/>
   <meta name="book-type" content="children"/>

2. Set viewport dimensions:

   Include viewport settings in each content document:

   <meta name="viewport" content="width=1600, height=2560"/>

3. Create device-specific versions:

   Fixed-layout books often need different versions for different platforms:

   • Kindle fixed-layout (.kf8)
   • EPUB3 fixed-layout (for Apple Books, Kobo)
   • PDF as a fallback for maximum compatibility
4. Test on target devices:

   Preview on actual devices or accurate simulators for each platform you plan to publish on.

Error: Text Overlay Issues in Fixed-Layout Books

Causes:

• Incorrect positioning of text layers over image backgrounds
• Font availability issues on target devices
• Pop-up text features not properly implemented
• Z-index and layering problems

Solutions:

1. Use absolute positioning carefully:

   .text-layer {
       position: absolute;
       top: 120px;
       left: 50px;
       width: 400px;
       z-index: 2;
   }
   
   .image-background {
       position: absolute;
       top: 0;
       left: 0;
       width: 100%;
       height: 100%;
       z-index: 1;
   }

2. Implement proper text pop-ups for Kindle:

   <div id="page1-image">
       <img src="page1.jpg" alt="Page 1 background" />
       <div class="text-block" id="text1">
           <a class="app-amzn-magnify" 
              data-app-amzn-magnify='{"targetId":"text1-popup", "sourcePosition": "entire", "ordinalNum": "1"}'>
               Text visible on page
           </a>
       </div>
   </div>
   
   <div id="text1-popup" class="popup">
       Full readable text that appears when tapped
   </div>

3. Embed fonts to ensure consistency:

   Include font files in your e-book package and specify them in CSS:

   @font-face {
       font-family: 'MyCustomFont';
       src: url('../fonts/mycustomfont.woff2') format('woff2'),
            url('../fonts/mycustomfont.woff') format('woff');
       font-weight: normal;
       font-style: normal;
   }

4. Use SVG for complex text positioning:

   For precise text placement, consider using SVG with embedded text elements:

   <svg xmlns="http://www.w3.org/2000/svg" width="1600" height="2560" viewBox="0 0 1600 2560">
       <image xlink:href="page_background.jpg" width="1600" height="2560" />
       <text x="200" y="500" font-family="MyCustomFont" font-size="48">Precisely positioned text</text>
   </svg>

DRM-Related E-book Errors

Digital Rights Management (DRM) protection can lead to various access and compatibility problems for legitimate e-book owners.

Error: "Unable to Open, DRM Restrictions" or Authorization Issues

Causes:

• E-book opened on an unauthorized device
• Adobe Digital Editions or other DRM handler not properly authorized
• Expired time-limited license
• Account issues with the e-book retailer

Solutions:

1. Authorize your reading device or software:

   For Adobe DRM (used by many EPUB retailers):

   1. Create an Adobe ID at account.adobe.com
   2. Install Adobe Digital Editions
   3. Authorize your computer: Help → Authorize Computer
   4. Enter your Adobe ID credentials
2. Deauthorize and reauthorize your account:

   If experiencing persistent issues, try resetting your authorization:

   1. In Adobe Digital Editions: Help → Deauthorize Computer
   2. Sign out of your e-book retailer's app
   3. Sign back in and reauthorize
3. For Kindle content problems:

   Make sure your device is registered to the correct Amazon account:

   1. On Kindle e-readers: Menu → Settings → Registration
   2. In Kindle app: Settings → Registration
   3. Try deregistering and re-registering the device
4. Check for device limit issues:

   Some DRM systems limit the number of devices that can access content simultaneously:

   • Remove authorization from unused devices
   • Contact the retailer to reset your device count if you've replaced devices

Error: Transferred E-books Not Working Across Devices

Causes:

• DRM license not transferred with the file
• Attempting to use incompatible DRM systems
• Manually copying files instead of using authorized transfer methods

Solutions:

1. Use the retailer's official apps and sync methods:

   Always download content directly to devices using official apps:

   • Kindle: Use "Deliver to" feature in Amazon account
   • Apple Books: Use iCloud sync across devices
   • Kobo: Use Kobo account sync
2. Transfer using authorized software:

   For Adobe DRM-protected EPUBs, use Adobe Digital Editions:

   1. Connect e-reader via USB
   2. Open Adobe Digital Editions
   3. Your device should appear under "Devices"
   4. Drag books to your device icon to transfer with DRM licenses intact
3. Check if format conversion is necessary:

   Some formats won't transfer between different ecosystems due to DRM:

   • Kindle books can only be read on Kindle devices and apps
   • Apple's iBooks format is limited to Apple devices

   Use the book in its native ecosystem or contact the retailer about format options.

4. Legal alternatives for persistent DRM issues:

   If DRM is causing problems with legitimately purchased content:

   • Contact the retailer's customer service for assistance
   • Request a different format if available
   • Some publishers offer DRM-free versions upon proof of purchase

E-book Conversion Errors

Converting between e-book formats often introduces errors and formatting issues that need to be addressed.

Error: Lost Formatting After Conversion

Causes:

• Target format doesn't support all features of the source format
• Complex layouts not translating between formats
• Font and typography differences
• Incorrect conversion settings

Solutions:

1. Use the appropriate conversion tool:

   Different tools excel at different conversion paths:

   • Calibre - Best all-around converter with extensive options
   • Kindle Previewer - Best for EPUB to Kindle format conversions
   • Pandoc - Excellent for conversions from/to markdown and other text formats
2. Tweak conversion settings:

   In Calibre, customize conversion options:

   • Look & Feel → Font size mapping
   • Page Setup → Output profile (match target device)
   • Structure Detection → Chapter mark
   • Table of Contents → Level 1, 2, 3 TOC (XPath expressions)
3. Pre-process source files:

   Before conversion, simplify formatting that may cause issues:

   • Replace complex tables with images if necessary
   • Simplify nested CSS styles
   • Break complex files into smaller sections
4. Post-process converted files:

   After conversion, open and tweak the output:

   • Use Sigil to edit EPUB files
   • Add device-specific CSS
   • Fix any obvious formatting issues

Error: Missing Content After Conversion

Causes:

• Interactive or multimedia elements not supported in target format
• Structural elements (sidebars, callouts) lost in translation
• Image conversion issues
• Script or advanced feature removal

Solutions:

1. Check conversion logs:

   Review detailed conversion reports to identify what was lost:

   • In Calibre: Click the job icon to view the conversion log
   • In KindleGen: Review terminal output for warnings and errors
2. Replace unsupported elements:

   Modify the source to replace unsupported features:

   • Convert interactive elements to static alternatives
   • Replace video with key frame images and text descriptions
   • Convert complex tables to images with text alternatives
3. Convert in stages:

   For difficult conversions, use intermediate formats:

   # Example: DOCX → EPUB → MOBI rather than DOCX → MOBI
   calibre-ebook source.docx --output-format epub
   calibre-ebook output.epub --output-format mobi

4. Create format-specific versions:

   For professional publishing, maintain separate source files optimized for each target format rather than relying on conversion.

Error: File Size Bloat After Conversion

Causes:

• Unoptimized images carried over during conversion
• Redundant or bloated CSS
• Embedded fonts increasing file size
• Hidden or temporary files included in the package

Solutions:

1. Optimize images before conversion:

   # Batch optimize JPEGs
   mogrify -quality 75 -resize "1200x1200>" *.jpg
   
   # Batch optimize PNGs
   optipng -o5 *.png

2. Clean and minimize CSS:

   Use CSS optimization tools to remove unused rules and reduce file size:

   csso styles.css --output styles.min.css

3. Subset embedded fonts:

   Only include the characters actually used in your e-book:

   pyftsubset font.ttf --unicodes="U+0020-007F,U+00A0-00FF" --output-file=font-subset.ttf

4. Remove unnecessary files:

   Before packaging or converting, check for and remove:

   • Hidden OS files (.DS_Store, Thumbs.db)
   • Backup files (*.bak, *~)
   • Development files not needed in final output

E-reader Device Compatibility Issues

Different e-readers handle formats and features in different ways, causing compatibility challenges.

Error: Device-Specific Display Problems

Causes:

• Device has limited support for advanced formatting
• Older e-reader with outdated firmware
• Screen size and resolution differences affecting layout
• Color vs. grayscale display limitations

Solutions:

1. Create device-targeted styles:

   Use media queries and conditional styles:

   /* Base styles for all devices */
   body { font-size: 1em; }
   
   /* Kindle E-ink specific */
   @media amzn-kf8 {
       body { font-size: 1.1em; }
       img.color { -webkit-filter: grayscale(100%); }
   }
   
   /* iPad/tablet specific */
   @media (min-width: 768px) {
       .sidebar { float: right; width: 30%; }
   }

2. Test on device simulators:

   Use official previewing tools to identify device-specific issues:

   • Kindle Previewer for Amazon devices
   • Adobe Digital Editions for general EPUB testing
   • iBooks Author Preview for Apple Books
3. Provide fallbacks for advanced features:

   <video controls>
       <source src="video.mp4" type="video/mp4">
       <!-- Fallback for devices that don't support video -->
       <div class="video-fallback">
           <img src="video-poster.jpg" alt="Video poster image">
           <p>This device does not support video playback.</p>
       </div>
   </video>

4. Create device-specific editions:

   For critical publications, create optimized versions for major platforms:

   • EPUB3 standard edition
   • Kindle-optimized edition
   • Fixed-layout edition for graphic-heavy content
   • PDF fallback for maximum compatibility

Error: Font Display Issues Across Devices

Causes:

• Font embedding issues or missing font files
• Some e-readers ignore embedded fonts by default
• Unsupported font formats (e.g., TTF vs. WOFF)
• Font license restrictions preventing embedding

Solutions:

1. Use widely supported font formats:

   Include multiple formats for maximum compatibility:

   @font-face {
       font-family: 'MyBookFont';
       src: url('../fonts/mybookfont.woff2') format('woff2'),
            url('../fonts/mybookfont.woff') format('woff'),
            url('../fonts/mybookfont.ttf') format('truetype');
       font-weight: normal;
       font-style: normal;
   }

2. Specify fallback font stacks:

   body {
       font-family: 'MyBookFont', Georgia, 'Times New Roman', serif;
   }

   This ensures reasonable display even if custom fonts fail.

3. For Kindle, use special format-specific techniques:

   <!-- In content.opf -->
   <meta name="amzn:embed-font" content="true" />

   This helps ensure Kindle devices respect embedded fonts.

4. Consider using "safe" e-book fonts:

   Rely on fonts known to work well across e-readers:

   • Georgia, Times New Roman, Palatino for serif
   • Arial, Helvetica, Verdana for sans-serif
   • Courier New for monospace

Preventing E-book File Errors

Implement these best practices to minimize electronic publishing file errors from the start.

Develop a Robust E-book Workflow

• Start with clean source files:

  Whether using Word, InDesign, or HTML, ensure source documents use:

  • Proper heading structure for hierarchy
  • Paragraph and character styles instead of direct formatting
  • Clean, consistent formatting throughout
  • Properly optimized images
• Validate at every stage:

  Implement validation checkpoints throughout your workflow:

  • HTML validation before packaging
  • EPUB validation with EPUBCheck
  • Device testing on simulators and actual devices
• Use templates and automation:

  Create standard templates for different types of e-books to ensure consistency and reduce errors.

• Implement version control:

  Use a version control system like Git to track changes and maintain the ability to roll back problematic changes.

Maintain Multiple Format Masters

• Keep source files for different formats:

  Rather than relying solely on conversion, maintain optimized masters for each major format:

  • Print-ready PDF
  • EPUB3 reflowable
  • EPUB3 fixed layout (if needed)
  • Kindle-optimized files
• Document format-specific quirks:

  Keep a knowledge base of format-specific requirements and workarounds for quick reference.

• Implement automated testing:

  Create scripts to check for common format-specific errors in your workflow.

Follow E-book Best Practices

• Use semantic markup:

  Structure content with proper semantic tags:

  <section epub:type="chapter">
      <h1>Chapter Title</h1>
      <p>Content...</p>
      <aside epub:type="sidebar">
          <h2>Sidebar Title</h2>
          <p>Sidebar content...</p>
      </aside>
  </section>

• Keep CSS simple and compatible:

  Avoid complex CSS that may render poorly across devices:

  • Minimize absolute positioning
  • Use relative units (em, %) over fixed units (px)
  • Provide fallbacks for advanced CSS properties
• Optimize all assets:

  Keep file sizes reasonable for download and display:

  • Compress images appropriately
  • Subset fonts to include only needed characters
  • Remove unnecessary files and metadata
• Prioritize accessibility:

  Accessible e-books often have fewer rendering problems as well:

  • Include proper alt text for images
  • Use logical reading order
  • Implement proper navigation
  • Add language attributes

Testing Strategy for E-book Files

• Implement multi-device testing:

  Test on both simulators and actual devices, covering:

  • E-ink readers (Kindle, Kobo, Nook)
  • Tablet apps (iPad, Android tablets)
  • Phone apps (smaller screens)
  • Desktop applications
  • Web-based readers
• Test different reading settings:

  Verify e-book appearance with various user settings:

  • Font size changes (small, medium, large)
  • Font family changes
  • Background/text color changes
  • Line spacing adjustments
  • Night mode/dark mode
• Create a testing checklist:

  Develop a standardized quality assurance checklist covering:

  • Navigation testing (TOC, links)
  • Content completeness check
  • Image display verification
  • Typography and formatting review
  • Metadata accuracy