diff --git a/docs/focus-reading.md b/docs/focus-reading.md
new file mode 100644
index 00000000..5063e4b4
--- /dev/null
+++ b/docs/focus-reading.md
@@ -0,0 +1,33 @@
+# Focus Reading
+
+Focus Reading is a reading aid that bolds the first portion of each word, guiding your eyes to natural fixation points and helping you read faster with less effort. Some readers — particularly those with ADHD — find it helps them stay engaged with the text and reduces mind-wandering. It is inspired by the Bionic Reading technique.
+
+<img src="./images/focus-reading/focus-reading.jpg" height="500" alt="Comparison of the same page with and without Focus Reading enabled" />
+
+*Left: Focus Reading off. Right: Focus Reading on. Both using Literata.*
+
+## Enabling Focus Reading
+
+1. Open **Settings > Reader**
+2. Toggle **Focus Reading** on
+
+Toggling the setting will trigger a re-index of your current book, the same as when changing font settings. Once indexing is complete, page turns proceed as normal. No changes are made to your EPUB files.
+
+## Examples
+
+<img src="./images/focus-reading/focus-reading-notoserif.jpg" height="500" alt="Focus Reading with Noto Serif font" />
+
+*Focus Reading with Noto Serif font*
+
+<img src="./images/focus-reading/focus-reading-merriweather.jpg" height="500" alt="Focus Reading with Merriweather font" />
+
+*Focus Reading with Merriweather font*
+
+<img src="./images/focus-reading/focus-reading-atkinson.jpg" height="500" alt="Focus Reading with Atkinson Hyperlegible Next font" />
+
+*Focus Reading with Atkinson Hyperlegible Next font*
+
+## Notes
+
+- Focus Reading only applies to regular body text. Already-bold text (headings, emphasis) is left unchanged.
+- The setting is per-device, not per-book — it applies to all books while enabled.
diff --git a/docs/images/focus-reading/focus-reading-atkinson.jpg b/docs/images/focus-reading/focus-reading-atkinson.jpg
new file mode 100644
index 00000000..8ec77b10
Binary files /dev/null and b/docs/images/focus-reading/focus-reading-atkinson.jpg differ
diff --git a/docs/images/focus-reading/focus-reading-merriweather.jpg b/docs/images/focus-reading/focus-reading-merriweather.jpg
new file mode 100644
index 00000000..59d82371
Binary files /dev/null and b/docs/images/focus-reading/focus-reading-merriweather.jpg differ
diff --git a/docs/images/focus-reading/focus-reading-notoserif.jpg b/docs/images/focus-reading/focus-reading-notoserif.jpg
new file mode 100644
index 00000000..8ffc869d
Binary files /dev/null and b/docs/images/focus-reading/focus-reading-notoserif.jpg differ
diff --git a/docs/images/focus-reading/focus-reading.jpg b/docs/images/focus-reading/focus-reading.jpg
new file mode 100644
index 00000000..97318e7b
Binary files /dev/null and b/docs/images/focus-reading/focus-reading.jpg differ
diff --git a/lib/Epub/Epub/ParsedText.cpp b/lib/Epub/Epub/ParsedText.cpp
index 6f31f5f2..193b320e 100644
--- a/lib/Epub/Epub/ParsedText.cpp
+++ b/lib/Epub/Epub/ParsedText.cpp
@@ -74,21 +74,170 @@ uint16_t measureWordWidth(const GfxRenderer& renderer, const int fontId, const s
   return renderer.getTextAdvanceX(fontId, sanitized.c_str(), style);
 }
 
+// Checks if a UTF-8 codepoint should be counted as part of a word for Focus Reading
+bool isWordCharacter(uint32_t cp) {
+  // ASCII range (Catches 95%+ of characters immediately)
+  if (cp < 128) {
+    // Bitwise trick: (cp | 0x20) converts uppercase ASCII to lowercase.
+    // This checks for A-Z and a-z mathematically, avoiding memory lookups and <cctype>
+    return ((cp | 0x20) >= 'a' && (cp | 0x20) <= 'z') || cp == '\'';
+  }
+
+  // General Punctuation Block, Currency, Math, Arrows, & Symbols (0x2000 - 0x2BFF)
+  if (cp >= 0x2000 && cp <= 0x2BFF) {
+    // Explicitly allow smart quotes, reject all other general punctuation (em-dashes, etc.)
+    return cp == 0x2018 || cp == 0x2019;
+  }
+
+  // Latin-1 Punctuation Block (0x00A1 - 0x00BF)
+  if (cp >= 0x00A1 && cp <= 0x00BF) {
+    // Allow ordinal indicators and micro sign, reject the rest (¡, ¿, «, », etc.)
+    return cp == 0x00AA || cp == 0x00B5 || cp == 0x00BA;
+  }
+
+  // Rejects Two-em dash, Three-em dash, Double oblique hyphen, etc.
+  if (cp >= 0x2E00 && cp <= 0x2E7F) return false;
+
+  // Rejects Modifier Minus (0x02D7), Small Hyphen (0xFE63), and Fullwidth Hyphen (0xFF0D)
+  if (cp == 0x02D7 || cp == 0xFE63 || cp == 0xFF0D) return false;
+  // Assume all other Unicode ranges (accented letters, Cyrillic, Greek, etc.) are valid
+
+  return true;
+}
+
 }  // namespace
 
 void ParsedText::addWord(std::string word, const EpdFontFamily::Style fontStyle, const bool underline,
                          const bool attachToPrevious) {
   if (word.empty()) return;
 
-  words.push_back(std::move(word));
-  EpdFontFamily::Style combinedStyle = fontStyle;
+  EpdFontFamily::Style baseStyle = fontStyle;
   if (underline) {
-    combinedStyle = static_cast<EpdFontFamily::Style>(combinedStyle | EpdFontFamily::UNDERLINE);
+    baseStyle = static_cast<EpdFontFamily::Style>(baseStyle | EpdFontFamily::UNDERLINE);
   }
-  wordStyles.push_back(combinedStyle);
-  wordContinues.push_back(attachToPrevious);
-}
 
+  // Already-bold text should stay fully bold; focus splitting would make its suffix regular later.
+  if (!this->focusReadingEnabled || (baseStyle & EpdFontFamily::BOLD) != 0) {
+    words.push_back(std::move(word));
+    wordStyles.push_back(baseStyle);
+    wordContinues.push_back(attachToPrevious);
+    wordIsFocusSuffix.push_back(false);
+    return;
+  }
+
+  // --- FOCUS READING LOGIC BELOW ---
+
+  // Pre-reserve capacity to prevent mid-word heap reallocations.
+  size_t maxPossibleNewTokens = word.length();
+  size_t requiredSize = words.size() + maxPossibleNewTokens;
+
+  if (words.capacity() < requiredSize) {
+    // Emulate standard geometric growth (doubling) to ensure we don't reallocate on every word.
+    size_t newCapacity = words.capacity() * 2;
+
+    // Ensure the doubled capacity is actually enough for this specific word
+    if (newCapacity < requiredSize) {
+      newCapacity = requiredSize;
+    }
+    // Set a sensible minimum starting size so the first few words don't trigger tiny reallocations
+    if (newCapacity < 16) {
+      newCapacity = 16;
+    }
+
+    words.reserve(newCapacity);
+    wordStyles.reserve(newCapacity);
+    wordContinues.reserve(newCapacity);
+    wordIsFocusSuffix.reserve(newCapacity);
+  }
+
+  // Lambda helper to process and push individual sub-segments of the string
+  // Use std::string_view to avoid heap allocations when slicing
+  auto processSegment = [&](std::string_view segment, bool isWord, bool attach) {
+    if (!isWord) {
+      // Punctuation and Numbers stay regular
+      words.emplace_back(segment);
+      wordStyles.push_back(baseStyle);
+      wordContinues.push_back(attach);
+      wordIsFocusSuffix.push_back(false);
+    } else {
+      size_t charCount = 0;
+      const unsigned char* countPtr = reinterpret_cast<const unsigned char*>(segment.data());
+      const unsigned char* countEnd = countPtr + segment.length();
+
+      while (countPtr < countEnd) {
+        utf8NextCodepoint(&countPtr);
+        charCount++;
+      }
+
+      // Target 45% for 1-bold at 4 chars and 3-bold at 7 chars with floor truncation
+      constexpr size_t FOCUS_READING_PERCENT = 45;
+      size_t targetBoldChars = (charCount * FOCUS_READING_PERCENT) / 100;
+      targetBoldChars = std::clamp<size_t>(targetBoldChars, 1, 9);
+
+      if (targetBoldChars >= charCount) {
+        // Whole segment is bold - no suffix split needed
+        words.emplace_back(segment);
+        wordStyles.push_back(static_cast<EpdFontFamily::Style>(baseStyle | EpdFontFamily::BOLD));
+        wordContinues.push_back(attach);
+        wordIsFocusSuffix.push_back(false);
+      } else {
+        countPtr = reinterpret_cast<const unsigned char*>(segment.data());
+        for (size_t i = 0; i < targetBoldChars; ++i) {
+          utf8NextCodepoint(&countPtr);
+        }
+        size_t splitByteOffset = countPtr - reinterpret_cast<const unsigned char*>(segment.data());
+
+        // Bold prefix
+        words.emplace_back(segment.substr(0, splitByteOffset));
+        wordStyles.push_back(static_cast<EpdFontFamily::Style>(baseStyle | EpdFontFamily::BOLD));
+        wordContinues.push_back(attach);
+        wordIsFocusSuffix.push_back(false);
+
+        // Regular suffix - marked so extractLine can merge it back into single TextBlock entry
+        words.emplace_back(segment.substr(splitByteOffset));
+        wordStyles.push_back(baseStyle);
+        wordContinues.push_back(true);
+        wordIsFocusSuffix.push_back(true);
+      }
+    }
+  };
+
+  // Tokenize the string by alternating states (Word vs. Non-Word)
+  const unsigned char* ptr = reinterpret_cast<const unsigned char*>(word.c_str());
+  const unsigned char* end = ptr + word.length();
+
+  const unsigned char* segmentStart = ptr;
+  uint32_t firstCp = utf8NextCodepoint(&ptr);  // Consume the first char to determine initial state
+  bool inWordSegment = isWordCharacter(firstCp);
+
+  bool isFirstSegment = true;
+
+  while (ptr < end) {
+    const unsigned char* currentCpStart = ptr;
+    uint32_t cp = utf8NextCodepoint(&ptr);
+    bool isWordChar = isWordCharacter(cp);
+
+    // Whenever the character type flips, slice off the segment we just completed and process it
+    if (isWordChar != inWordSegment) {
+      size_t segmentLen = currentCpStart - segmentStart;
+      std::string_view segment(reinterpret_cast<const char*>(segmentStart), segmentLen);
+
+      // Only the very first segment inherits the original attachToPrevious flag.
+      // Every subsequent segment MUST attach=true so it glues seamlessly to the prefix.
+      processSegment(segment, inWordSegment, isFirstSegment ? attachToPrevious : true);
+
+      // Setup for the next segment
+      segmentStart = currentCpStart;
+      inWordSegment = isWordChar;
+      isFirstSegment = false;
+    }
+  }
+
+  // Process the final remaining segment
+  size_t segmentLen = end - segmentStart;
+  std::string_view segment(reinterpret_cast<const char*>(segmentStart), segmentLen);
+  processSegment(segment, inWordSegment, isFirstSegment ? attachToPrevious : true);
+}
 // Consumes data to minimize memory usage
 void ParsedText::layoutAndExtractLines(const GfxRenderer& renderer, const int fontId, const uint16_t viewportWidth,
                                        const std::function<void(std::shared_ptr<TextBlock>)>& processLine,
@@ -153,6 +302,7 @@ void ParsedText::layoutAndExtractLines(const GfxRenderer& renderer, const int fo
     words.erase(words.begin(), words.begin() + consumed);
     wordStyles.erase(wordStyles.begin(), wordStyles.begin() + consumed);
     wordContinues.erase(wordContinues.begin(), wordContinues.begin() + consumed);
+    wordIsFocusSuffix.erase(wordIsFocusSuffix.begin(), wordIsFocusSuffix.begin() + consumed);
   }
 }
 
@@ -436,6 +586,8 @@ bool ParsedText::hyphenateWordAtIndex(const size_t wordIndex, const int availabl
   // Insert the remainder word (with matching style and continuation flag) directly after the prefix.
   words.insert(words.begin() + wordIndex + 1, remainder);
   wordStyles.insert(wordStyles.begin() + wordIndex + 1, style);
+  // The hyphen remainder is not a focus suffix - it starts fresh on the next line.
+  wordIsFocusSuffix.insert(wordIsFocusSuffix.begin() + wordIndex + 1, false);
 
   // Continuation flag handling after splitting a word into prefix + remainder.
   //
@@ -567,6 +719,63 @@ void ParsedText::extractLine(const size_t breakIndex, const int pageWidth, const
     }
   }
 
-  processLine(
-      std::make_shared<TextBlock>(std::move(lineWords), std::move(lineXPos), std::move(lineWordStyles), blockStyle));
+  // Fast path: when no word on this line was split for focus reading, skip the merge work
+  // entirely and pass empty boundary/suffixX vectors. TextBlock pays zero per-word RAM cost
+  // for these annotations when the vectors are empty.
+  bool lineHasFocusSplit = false;
+  for (size_t i = 0; i < lineWordCount; i++) {
+    if (wordIsFocusSuffix[lastBreakAt + i]) {
+      lineHasFocusSplit = true;
+      break;
+    }
+  }
+
+  if (!lineHasFocusSplit) {
+    processLine(std::make_shared<TextBlock>(std::move(lineWords), std::move(lineXPos), std::move(lineWordStyles),
+                                            std::vector<uint8_t>{}, std::vector<uint16_t>{}, blockStyle));
+    return;
+  }
+
+  // Slow path: merge focus suffix tokens back into their preceding word entry so each
+  // original word occupies one TextBlock slot. Splits are recorded as per-word annotations
+  // applied at render time, cutting the token count significantly when the feature is active.
+  std::vector<std::string> outWords;
+  std::vector<int16_t> outXPos;
+  std::vector<EpdFontFamily::Style> outStyles;
+  std::vector<uint8_t> outBoundaries;
+  std::vector<uint16_t> outSuffixX;
+  outWords.reserve(lineWordCount);
+  outXPos.reserve(lineWordCount);
+  outStyles.reserve(lineWordCount);
+  outBoundaries.reserve(lineWordCount);
+  outSuffixX.reserve(lineWordCount);
+
+  for (size_t i = 0; i < lineWordCount; i++) {
+    if (wordIsFocusSuffix[lastBreakAt + i] && !outWords.empty()) {
+      // Focus suffix: merge string into the preceding bold-prefix entry.
+      outWords.back() += lineWords[i];
+    } else {
+      // Normal word: check for a following focus suffix to record the byte boundary.
+      uint8_t boundary = 0;
+      uint16_t suffixX = 0;
+      if (i + 1 < lineWordCount && wordIsFocusSuffix[lastBreakAt + i + 1]) {
+        boundary = static_cast<uint8_t>(std::min(lineWords[i].size(), size_t{255}));
+        // Suffix x offset = layout-time advance of the bold prefix, already known from xpos table.
+        suffixX = static_cast<uint16_t>(lineXPos[i + 1] - lineXPos[i]);
+      }
+      outWords.push_back(std::move(lineWords[i]));
+      outXPos.push_back(lineXPos[i]);
+      // For focus entries with a suffix, strip BOLD from the stored style.
+      // Render re-applies it to the prefix portion only, via the boundary field.
+      const EpdFontFamily::Style storedStyle =
+          boundary > 0 ? static_cast<EpdFontFamily::Style>(lineWordStyles[i] & ~EpdFontFamily::BOLD)
+                       : lineWordStyles[i];
+      outStyles.push_back(storedStyle);
+      outBoundaries.push_back(boundary);
+      outSuffixX.push_back(suffixX);
+    }
+  }
+
+  processLine(std::make_shared<TextBlock>(std::move(outWords), std::move(outXPos), std::move(outStyles),
+                                          std::move(outBoundaries), std::move(outSuffixX), blockStyle));
 }
diff --git a/lib/Epub/Epub/ParsedText.h b/lib/Epub/Epub/ParsedText.h
index 9d43400e..167d3d26 100644
--- a/lib/Epub/Epub/ParsedText.h
+++ b/lib/Epub/Epub/ParsedText.h
@@ -15,10 +15,12 @@ class GfxRenderer;
 class ParsedText {
   std::vector<std::string> words;
   std::vector<EpdFontFamily::Style> wordStyles;
-  std::vector<bool> wordContinues;  // true = word attaches to previous (no space before it)
+  std::vector<bool> wordContinues;      // true = word attaches to previous (no space before it)
+  std::vector<bool> wordIsFocusSuffix;  // true = token is the regular tail of a focus bold-prefix split
   BlockStyle blockStyle;
   bool extraParagraphSpacing;
   bool hyphenationEnabled;
+  bool focusReadingEnabled;
 
   void applyParagraphIndent();
   std::vector<size_t> computeLineBreaks(const GfxRenderer& renderer, int fontId, int pageWidth,
@@ -35,8 +37,11 @@ class ParsedText {
 
  public:
   explicit ParsedText(const bool extraParagraphSpacing, const bool hyphenationEnabled = false,
-                      const BlockStyle& blockStyle = BlockStyle())
-      : blockStyle(blockStyle), extraParagraphSpacing(extraParagraphSpacing), hyphenationEnabled(hyphenationEnabled) {}
+                      const bool focusReadingEnabled = false, const BlockStyle& blockStyle = BlockStyle())
+      : blockStyle(blockStyle),
+        extraParagraphSpacing(extraParagraphSpacing),
+        hyphenationEnabled(hyphenationEnabled),
+        focusReadingEnabled(focusReadingEnabled) {}
   ~ParsedText() = default;
 
   void addWord(std::string word, EpdFontFamily::Style fontStyle, bool underline = false, bool attachToPrevious = false);
diff --git a/lib/Epub/Epub/Section.cpp b/lib/Epub/Epub/Section.cpp
index 57a92cd8..7cbd37e1 100644
--- a/lib/Epub/Epub/Section.cpp
+++ b/lib/Epub/Epub/Section.cpp
@@ -13,8 +13,8 @@ namespace {
 constexpr uint8_t SECTION_FILE_VERSION = 23;
 constexpr uint32_t HEADER_SIZE = sizeof(uint8_t) + sizeof(int) + sizeof(float) + sizeof(bool) + sizeof(uint8_t) +
                                  sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(bool) + sizeof(bool) +
-                                 sizeof(uint8_t) + sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint32_t) +
-                                 sizeof(uint32_t);
+                                 sizeof(uint8_t) + sizeof(bool) + sizeof(uint32_t) + sizeof(uint32_t) +
+                                 sizeof(uint32_t) + sizeof(uint32_t);
 
 struct PageLutEntry {
   uint32_t fileOffset;
@@ -43,7 +43,8 @@ uint32_t Section::onPageComplete(std::unique_ptr<Page> page) {
 void Section::writeSectionFileHeader(const int fontId, const float lineCompression, const bool extraParagraphSpacing,
                                      const uint8_t paragraphAlignment, const uint16_t viewportWidth,
                                      const uint16_t viewportHeight, const bool hyphenationEnabled,
-                                     const bool embeddedStyle, const uint8_t imageRendering) {
+                                     const bool embeddedStyle, const uint8_t imageRendering,
+                                     const bool focusReadingEnabled) {
   if (!file) {
     LOG_DBG("SCT", "File not open for writing header");
     return;
@@ -51,8 +52,8 @@ void Section::writeSectionFileHeader(const int fontId, const float lineCompressi
   static_assert(HEADER_SIZE == sizeof(SECTION_FILE_VERSION) + sizeof(fontId) + sizeof(lineCompression) +
                                    sizeof(extraParagraphSpacing) + sizeof(paragraphAlignment) + sizeof(viewportWidth) +
                                    sizeof(viewportHeight) + sizeof(pageCount) + sizeof(hyphenationEnabled) +
-                                   sizeof(embeddedStyle) + sizeof(imageRendering) + sizeof(uint32_t) +
-                                   sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint32_t),
+                                   sizeof(embeddedStyle) + sizeof(imageRendering) + sizeof(focusReadingEnabled) +
+                                   sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint32_t) + sizeof(uint32_t),
                 "Header size mismatch");
   serialization::writePod(file, SECTION_FILE_VERSION);
   serialization::writePod(file, fontId);
@@ -64,6 +65,7 @@ void Section::writeSectionFileHeader(const int fontId, const float lineCompressi
   serialization::writePod(file, hyphenationEnabled);
   serialization::writePod(file, embeddedStyle);
   serialization::writePod(file, imageRendering);
+  serialization::writePod(file, focusReadingEnabled);
   serialization::writePod(file, pageCount);  // Placeholder for page count (will be initially 0, patched later)
   serialization::writePod(file, static_cast<uint32_t>(0));  // Placeholder for LUT offset (patched later)
   serialization::writePod(file, static_cast<uint32_t>(0));  // Placeholder for anchor map offset (patched later)
@@ -74,7 +76,7 @@ void Section::writeSectionFileHeader(const int fontId, const float lineCompressi
 bool Section::loadSectionFile(const int fontId, const float lineCompression, const bool extraParagraphSpacing,
                               const uint8_t paragraphAlignment, const uint16_t viewportWidth,
                               const uint16_t viewportHeight, const bool hyphenationEnabled, const bool embeddedStyle,
-                              const uint8_t imageRendering) {
+                              const uint8_t imageRendering, const bool focusReadingEnabled) {
   if (!Storage.openFileForRead("SCT", filePath, file)) {
     return false;
   }
@@ -99,6 +101,7 @@ bool Section::loadSectionFile(const int fontId, const float lineCompression, con
     bool fileHyphenationEnabled;
     bool fileEmbeddedStyle;
     uint8_t fileImageRendering;
+    bool fileFocusReadingEnabled;
     serialization::readPod(file, fileFontId);
     serialization::readPod(file, fileLineCompression);
     serialization::readPod(file, fileExtraParagraphSpacing);
@@ -108,13 +111,13 @@ bool Section::loadSectionFile(const int fontId, const float lineCompression, con
     serialization::readPod(file, fileHyphenationEnabled);
     serialization::readPod(file, fileEmbeddedStyle);
     serialization::readPod(file, fileImageRendering);
+    serialization::readPod(file, fileFocusReadingEnabled);
 
     if (fontId != fileFontId || lineCompression != fileLineCompression ||
         extraParagraphSpacing != fileExtraParagraphSpacing || paragraphAlignment != fileParagraphAlignment ||
         viewportWidth != fileViewportWidth || viewportHeight != fileViewportHeight ||
         hyphenationEnabled != fileHyphenationEnabled || embeddedStyle != fileEmbeddedStyle ||
-        imageRendering != fileImageRendering) {
-      // Explicit close() required: member variable persists beyond function scope
+        imageRendering != fileImageRendering || focusReadingEnabled != fileFocusReadingEnabled) {
       file.close();
       LOG_ERR("SCT", "Deserialization failed: Parameters do not match");
       clearCache();
@@ -148,7 +151,8 @@ bool Section::clearCache() const {
 bool Section::createSectionFile(const int fontId, const float lineCompression, const bool extraParagraphSpacing,
                                 const uint8_t paragraphAlignment, const uint16_t viewportWidth,
                                 const uint16_t viewportHeight, const bool hyphenationEnabled, const bool embeddedStyle,
-                                const uint8_t imageRendering, const std::function<void()>& popupFn) {
+                                const uint8_t imageRendering, const bool focusReadingEnabled,
+                                const std::function<void()>& popupFn) {
   const auto localPath = epub->getSpineItem(spineIndex).href;
   const auto tmpHtmlPath = epub->getCachePath() + "/.tmp_" + std::to_string(spineIndex) + ".html";
 
@@ -199,7 +203,7 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
     return false;
   }
   writeSectionFileHeader(fontId, lineCompression, extraParagraphSpacing, paragraphAlignment, viewportWidth,
-                         viewportHeight, hyphenationEnabled, embeddedStyle, imageRendering);
+                         viewportHeight, hyphenationEnabled, embeddedStyle, imageRendering, focusReadingEnabled);
   std::vector<PageLutEntry> lut = {};
 
   // Derive the content base directory and image cache path prefix for the parser
@@ -219,7 +223,7 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
 
   ChapterHtmlSlimParser visitor(
       epub, tmpHtmlPath, renderer, fontId, lineCompression, extraParagraphSpacing, paragraphAlignment, viewportWidth,
-      viewportHeight, hyphenationEnabled,
+      viewportHeight, hyphenationEnabled, focusReadingEnabled,
       [this, &lut](std::unique_ptr<Page> page, const uint16_t paragraphIndex, const uint16_t listItemIndex) {
         lut.push_back({this->onPageComplete(std::move(page)), paragraphIndex, listItemIndex});
       },
diff --git a/lib/Epub/Epub/Section.h b/lib/Epub/Epub/Section.h
index 9688e276..aea02d34 100644
--- a/lib/Epub/Epub/Section.h
+++ b/lib/Epub/Epub/Section.h
@@ -18,7 +18,7 @@ class Section {
 
   void writeSectionFileHeader(int fontId, float lineCompression, bool extraParagraphSpacing, uint8_t paragraphAlignment,
                               uint16_t viewportWidth, uint16_t viewportHeight, bool hyphenationEnabled,
-                              bool embeddedStyle, uint8_t imageRendering);
+                              bool embeddedStyle, uint8_t imageRendering, bool focusReadingEnabled);
   uint32_t onPageComplete(std::unique_ptr<Page> page);
 
  public:
@@ -33,11 +33,12 @@ class Section {
   ~Section() = default;
   bool loadSectionFile(int fontId, float lineCompression, bool extraParagraphSpacing, uint8_t paragraphAlignment,
                        uint16_t viewportWidth, uint16_t viewportHeight, bool hyphenationEnabled, bool embeddedStyle,
-                       uint8_t imageRendering);
+                       uint8_t imageRendering, bool focusReadingEnabled);
   bool clearCache() const;
   bool createSectionFile(int fontId, float lineCompression, bool extraParagraphSpacing, uint8_t paragraphAlignment,
                          uint16_t viewportWidth, uint16_t viewportHeight, bool hyphenationEnabled, bool embeddedStyle,
-                         uint8_t imageRendering, const std::function<void()>& popupFn = nullptr);
+                         uint8_t imageRendering, bool focusReadingEnabled,
+                         const std::function<void()>& popupFn = nullptr);
   std::unique_ptr<Page> loadPageFromSectionFile();
 
   // Look up the page number for an anchor id from the section cache file.
diff --git a/lib/Epub/Epub/blocks/TextBlock.cpp b/lib/Epub/Epub/blocks/TextBlock.cpp
index e3e35d42..9acd8b03 100644
--- a/lib/Epub/Epub/blocks/TextBlock.cpp
+++ b/lib/Epub/Epub/blocks/TextBlock.cpp
@@ -4,18 +4,44 @@
 #include <Logging.h>
 #include <Serialization.h>
 
+#include <cstring>
+
 void TextBlock::render(const GfxRenderer& renderer, const int fontId, const int x, const int y) const {
-  // Validate iterator bounds before rendering
-  if (words.size() != wordXpos.size() || words.size() != wordStyles.size()) {
-    LOG_ERR("TXB", "Render skipped: size mismatch (words=%u, xpos=%u, styles=%u)\n", (uint32_t)words.size(),
-            (uint32_t)wordXpos.size(), (uint32_t)wordStyles.size());
+  // Focus annotations are optional: empty vectors mean no word in this block has a split.
+  // When present, they must be sized in lockstep with words[].
+  const bool hasFocus = !wordFocusBoundary.empty();
+  if (words.size() != wordXpos.size() || words.size() != wordStyles.size() ||
+      (hasFocus && (words.size() != wordFocusBoundary.size() || words.size() != wordFocusSuffixX.size()))) {
+    LOG_ERR("TXB", "Render skipped: size mismatch (words=%u, xpos=%u, styles=%u, boundary=%u, suffixX=%u)\n",
+            (uint32_t)words.size(), (uint32_t)wordXpos.size(), (uint32_t)wordStyles.size(),
+            (uint32_t)wordFocusBoundary.size(), (uint32_t)wordFocusSuffixX.size());
     return;
   }
 
   for (size_t i = 0; i < words.size(); i++) {
     const int wordX = wordXpos[i] + x;
     const EpdFontFamily::Style currentStyle = wordStyles[i];
-    renderer.drawText(fontId, wordX, y, words[i].c_str(), true, currentStyle);
+    const uint8_t boundary = hasFocus ? wordFocusBoundary[i] : 0;
+
+    if (boundary > 0) {
+      // Focus split: draw bold prefix, then the regular suffix at a pre-computed x offset.
+      // The bold prefix is bounded to 9 codepoints by the clamp on targetBoldChars in
+      // ParsedText::addWord; 9 UTF-8 codepoints occupy at most 9 * 4 = 36 bytes, +1 for null = 37.
+      // suffixX is computed at cache-creation time to avoid font metric lookups at render time.
+      static constexpr size_t MAX_FOCUS_PREFIX_BYTES = 9 * 4 + 1;
+      char boldBuf[40];
+      static_assert(sizeof(boldBuf) >= MAX_FOCUS_PREFIX_BYTES,
+                    "boldBuf too small for max focus prefix (9 codepoints * 4 UTF-8 bytes + null)");
+      const auto boldStyle = static_cast<EpdFontFamily::Style>(currentStyle | EpdFontFamily::BOLD);
+      const size_t boldLen = std::min<size_t>({static_cast<size_t>(boundary), words[i].size(), sizeof(boldBuf) - 1});
+      memcpy(boldBuf, words[i].c_str(), boldLen);
+      boldBuf[boldLen] = '\0';
+      renderer.drawText(fontId, wordX, y, boldBuf, true, boldStyle);
+      const int suffixX = wordX + wordFocusSuffixX[i];
+      renderer.drawText(fontId, suffixX, y, words[i].c_str() + boldLen, true, currentStyle);
+    } else {
+      renderer.drawText(fontId, wordX, y, words[i].c_str(), true, currentStyle);
+    }
 
     if ((currentStyle & EpdFontFamily::UNDERLINE) != 0) {
       const std::string& w = words[i];
@@ -42,9 +68,15 @@ void TextBlock::render(const GfxRenderer& renderer, const int fontId, const int
 }
 
 bool TextBlock::serialize(FsFile& file) const {
-  if (words.size() != wordXpos.size() || words.size() != wordStyles.size()) {
-    LOG_ERR("TXB", "Serialization failed: size mismatch (words=%u, xpos=%u, styles=%u)\n", words.size(),
-            wordXpos.size(), wordStyles.size());
+  // Focus annotations are optional; vectors are either empty (no splits in this block)
+  // or sized in lockstep with words[].
+  const bool hasFocus = !wordFocusBoundary.empty();
+  if (words.size() != wordXpos.size() || words.size() != wordStyles.size() ||
+      (hasFocus && (words.size() != wordFocusBoundary.size() || words.size() != wordFocusSuffixX.size()))) {
+    LOG_ERR("TXB", "Serialization failed: size mismatch (words=%u, xpos=%u, styles=%u, boundary=%u, suffixX=%u)\n",
+            static_cast<uint32_t>(words.size()), static_cast<uint32_t>(wordXpos.size()),
+            static_cast<uint32_t>(wordStyles.size()), static_cast<uint32_t>(wordFocusBoundary.size()),
+            static_cast<uint32_t>(wordFocusSuffixX.size()));
     return false;
   }
 
@@ -53,6 +85,13 @@ bool TextBlock::serialize(FsFile& file) const {
   for (const auto& w : words) serialization::writeString(file, w);
   for (auto x : wordXpos) serialization::writePod(file, x);
   for (auto s : wordStyles) serialization::writePod(file, s);
+  // Focus block: 1-byte presence flag, followed by per-word vectors only when present.
+  // Saves 3 bytes/word when focus reading is disabled or no word on this line was split.
+  serialization::writePod(file, static_cast<uint8_t>(hasFocus ? 1 : 0));
+  if (hasFocus) {
+    for (auto b : wordFocusBoundary) serialization::writePod(file, b);
+    for (auto sx : wordFocusSuffixX) serialization::writePod(file, sx);
+  }
 
   // Style (alignment + margins/padding/indent)
   serialization::writePod(file, blockStyle.alignment);
@@ -76,6 +115,8 @@ std::unique_ptr<TextBlock> TextBlock::deserialize(FsFile& file) {
   std::vector<std::string> words;
   std::vector<int16_t> wordXpos;
   std::vector<EpdFontFamily::Style> wordStyles;
+  std::vector<uint8_t> wordFocusBoundary;
+  std::vector<uint16_t> wordFocusSuffixX;
   BlockStyle blockStyle;
 
   // Word count
@@ -94,6 +135,16 @@ std::unique_ptr<TextBlock> TextBlock::deserialize(FsFile& file) {
   for (auto& w : words) serialization::readString(file, w);
   for (auto& x : wordXpos) serialization::readPod(file, x);
   for (auto& s : wordStyles) serialization::readPod(file, s);
+  // Focus block: presence flag, then vectors only if present. Empty vectors when absent
+  // signal "no splits in this block" to render() (zero per-word RAM cost).
+  uint8_t hasFocus;
+  serialization::readPod(file, hasFocus);
+  if (hasFocus) {
+    wordFocusBoundary.resize(wc);
+    wordFocusSuffixX.resize(wc);
+    for (auto& b : wordFocusBoundary) serialization::readPod(file, b);
+    for (auto& sx : wordFocusSuffixX) serialization::readPod(file, sx);
+  }
 
   // Style (alignment + margins/padding/indent)
   serialization::readPod(file, blockStyle.alignment);
@@ -109,6 +160,7 @@ std::unique_ptr<TextBlock> TextBlock::deserialize(FsFile& file) {
   serialization::readPod(file, blockStyle.textIndent);
   serialization::readPod(file, blockStyle.textIndentDefined);
 
-  return std::unique_ptr<TextBlock>(
-      new TextBlock(std::move(words), std::move(wordXpos), std::move(wordStyles), blockStyle));
+  return std::unique_ptr<TextBlock>(new TextBlock(std::move(words), std::move(wordXpos), std::move(wordStyles),
+                                                  std::move(wordFocusBoundary), std::move(wordFocusSuffixX),
+                                                  blockStyle));
 }
diff --git a/lib/Epub/Epub/blocks/TextBlock.h b/lib/Epub/Epub/blocks/TextBlock.h
index 85fdd55a..e60b283c 100644
--- a/lib/Epub/Epub/blocks/TextBlock.h
+++ b/lib/Epub/Epub/blocks/TextBlock.h
@@ -15,14 +15,28 @@ class TextBlock final : public Block {
   std::vector<std::string> words;
   std::vector<int16_t> wordXpos;
   std::vector<EpdFontFamily::Style> wordStyles;
+  // Per-word focus boundary: N > 0 means the first N bytes of words[i] are rendered bold,
+  // the remainder in the base style. 0 means no split (whole word uses wordStyles[i]).
+  // N encodes the bold PREFIX length only — bounded to 9 codepoints (≤36 UTF-8 bytes) by
+  // FOCUS_READING_PERCENT's 1..9 clamp in ParsedText::addWord, so it always fits in uint8_t.
+  // Vector is empty when no focus splits exist anywhere in the block (zero per-word RAM cost
+  // when focus reading is disabled, or on lines that happen to contain no splittable words).
+  std::vector<uint8_t> wordFocusBoundary;
+  // Pre-computed pixel offset from word start to the regular suffix, stored when boundary > 0.
+  // Eliminates getTextAdvanceX from the render path. 0 when boundary == 0.
+  // Empty in lockstep with wordFocusBoundary.
+  std::vector<uint16_t> wordFocusSuffixX;
   BlockStyle blockStyle;
 
  public:
   explicit TextBlock(std::vector<std::string> words, std::vector<int16_t> word_xpos,
-                     std::vector<EpdFontFamily::Style> word_styles, const BlockStyle& blockStyle = BlockStyle())
+                     std::vector<EpdFontFamily::Style> word_styles, std::vector<uint8_t> focus_boundary,
+                     std::vector<uint16_t> focus_suffix_x, const BlockStyle& blockStyle = BlockStyle())
       : words(std::move(words)),
         wordXpos(std::move(word_xpos)),
         wordStyles(std::move(word_styles)),
+        wordFocusBoundary(std::move(focus_boundary)),
+        wordFocusSuffixX(std::move(focus_suffix_x)),
         blockStyle(blockStyle) {}
   ~TextBlock() override = default;
   void setBlockStyle(const BlockStyle& blockStyle) { this->blockStyle = blockStyle; }
diff --git a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
index c9f89e2e..a25a1dbd 100644
--- a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
+++ b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
@@ -141,7 +141,7 @@ void ChapterHtmlSlimParser::startNewTextBlock(const BlockStyle& blockStyle) {
     anchorData.push_back({std::move(pendingAnchorId), static_cast<uint16_t>(completedPageCount)});
     pendingAnchorId.clear();
   }
-  currentTextBlock.reset(new ParsedText(extraParagraphSpacing, hyphenationEnabled, blockStyle));
+  currentTextBlock.reset(new ParsedText(extraParagraphSpacing, hyphenationEnabled, focusReadingEnabled, blockStyle));
   wordsExtractedInBlock = 0;
 }
 
diff --git a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h
index 5802bb94..aeaea7f5 100644
--- a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h
+++ b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h
@@ -47,6 +47,7 @@ class ChapterHtmlSlimParser {
   uint16_t viewportWidth;
   uint16_t viewportHeight;
   bool hyphenationEnabled;
+  bool focusReadingEnabled;
   const CssParser* cssParser;
   bool embeddedStyle;
   uint8_t imageRendering;
@@ -101,6 +102,7 @@ class ChapterHtmlSlimParser {
                                  const int fontId, const float lineCompression, const bool extraParagraphSpacing,
                                  const uint8_t paragraphAlignment, const uint16_t viewportWidth,
                                  const uint16_t viewportHeight, const bool hyphenationEnabled,
+                                 const bool focusReadingEnabled,
                                  const std::function<void(std::unique_ptr<Page>, uint16_t, uint16_t)>& completePageFn,
                                  const bool embeddedStyle, const std::string& contentBase,
                                  const std::string& imageBasePath, const uint8_t imageRendering = 0,
@@ -116,6 +118,7 @@ class ChapterHtmlSlimParser {
         viewportWidth(viewportWidth),
         viewportHeight(viewportHeight),
         hyphenationEnabled(hyphenationEnabled),
+        focusReadingEnabled(focusReadingEnabled),
         completePageFn(completePageFn),
         popupFn(popupFn),
         cssParser(cssParser),
diff --git a/lib/I18n/translations/belarusian.yaml b/lib/I18n/translations/belarusian.yaml
index 245ecc10..f854cae8 100644
--- a/lib/I18n/translations/belarusian.yaml
+++ b/lib/I18n/translations/belarusian.yaml
@@ -259,6 +259,7 @@ STR_SECTION_PREFIX: "Раздзел"
 STR_UPLOAD: "Адправіць"
 STR_BOOK_S_STYLE: "Стыль кнігі"
 STR_EMBEDDED_STYLE: "Убудаваны стыль"
+STR_FOCUS_READING: "Фокуснае чытанне"
 STR_OPDS_SERVER_URL: "URL OPDS сервера"
 STR_SCREENSHOT_BUTTON: "Зрабіць здымак экрана"
 STR_IMAGES: "Выявы"
diff --git a/lib/I18n/translations/catalan.yaml b/lib/I18n/translations/catalan.yaml
index 377ab05e..40b02ea0 100644
--- a/lib/I18n/translations/catalan.yaml
+++ b/lib/I18n/translations/catalan.yaml
@@ -287,6 +287,7 @@ STR_SECTION_PREFIX: "Secció "
 STR_UPLOAD: "Puja"
 STR_BOOK_S_STYLE: "Estil del llibre"
 STR_EMBEDDED_STYLE: "Estil incrustat"
+STR_FOCUS_READING: "Lectura enfocada"
 STR_OPDS_SERVER_URL: "URL del servidor OPDS"
 STR_FOOTNOTES: "Notes al peu"
 STR_NO_FOOTNOTES: "No hi ha notes al peu en aquesta pàgina"
diff --git a/lib/I18n/translations/czech.yaml b/lib/I18n/translations/czech.yaml
index a769aa07..379bd690 100644
--- a/lib/I18n/translations/czech.yaml
+++ b/lib/I18n/translations/czech.yaml
@@ -264,6 +264,7 @@ STR_SECTION_PREFIX: "Sekce"
 STR_UPLOAD: "Nahrát"
 STR_BOOK_S_STYLE: "Styl knihy"
 STR_EMBEDDED_STYLE: "Vložený styl"
+STR_FOCUS_READING: "Soustředěné čtení"
 STR_OPDS_SERVER_URL: "URL serveru OPDS"
 STR_SCREENSHOT_BUTTON: "Udělat snímek obrazovky"
 STR_TILT_PAGE_TURN: "Otáčení stránek nakloněním"
diff --git a/lib/I18n/translations/danish.yaml b/lib/I18n/translations/danish.yaml
index 91b13025..9a1b979d 100644
--- a/lib/I18n/translations/danish.yaml
+++ b/lib/I18n/translations/danish.yaml
@@ -287,6 +287,7 @@ STR_SECTION_PREFIX: "Afsnit "
 STR_UPLOAD: "Upload"
 STR_BOOK_S_STYLE: "Bogens stil"
 STR_EMBEDDED_STYLE: "Indlejret stil"
+STR_FOCUS_READING: "Fokuslæsning"
 STR_OPDS_SERVER_URL: "OPDS Server URL"
 STR_FOOTNOTES: "Fodnoter"
 STR_NO_FOOTNOTES: "Ingen fodnoter på denne side"
diff --git a/lib/I18n/translations/dutch.yaml b/lib/I18n/translations/dutch.yaml
index 47041116..12593f0a 100644
--- a/lib/I18n/translations/dutch.yaml
+++ b/lib/I18n/translations/dutch.yaml
@@ -287,6 +287,7 @@ STR_SECTION_PREFIX: "Sectie "
 STR_UPLOAD: "Uploaden"
 STR_BOOK_S_STYLE: "Stijl van boek"
 STR_EMBEDDED_STYLE: "Ingebedde stijl"
+STR_FOCUS_READING: "Gefocust lezen"
 STR_OPDS_SERVER_URL: "OPDS-server URL"
 STR_FOOTNOTES: "Voetnoten"
 STR_NO_FOOTNOTES: "Geen voetnoten op deze pagina"
diff --git a/lib/I18n/translations/english.yaml b/lib/I18n/translations/english.yaml
index 969af61c..e9c5a192 100644
--- a/lib/I18n/translations/english.yaml
+++ b/lib/I18n/translations/english.yaml
@@ -296,6 +296,7 @@ STR_SECTION_PREFIX: "Section "
 STR_UPLOAD: "Upload"
 STR_BOOK_S_STYLE: "Book's Style"
 STR_EMBEDDED_STYLE: "Embedded Style"
+STR_FOCUS_READING: "Focus Reading"
 STR_OPDS_SERVER_URL: "OPDS Server URL"
 STR_SET_SLEEP_COVER: "Set Cover"
 STR_FOOTNOTES: "Footnotes"
diff --git a/lib/I18n/translations/finnish.yaml b/lib/I18n/translations/finnish.yaml
index 99a4d974..93672291 100644
--- a/lib/I18n/translations/finnish.yaml
+++ b/lib/I18n/translations/finnish.yaml
@@ -262,6 +262,7 @@ STR_SECTION_PREFIX: "Osio "
 STR_UPLOAD: "Lähetä"
 STR_BOOK_S_STYLE: "Kirjan tyyli"
 STR_EMBEDDED_STYLE: "Upotettu tyyli"
+STR_FOCUS_READING: "Keskittynyt lukeminen"
 STR_OPDS_SERVER_URL: "OPDS-palvelimen osoite"
 STR_SCREENSHOT_BUTTON: "Ota kuvakaappaus"
 STR_TILT_PAGE_TURN: "Sivunkääntö kallistamalla"
diff --git a/lib/I18n/translations/french.yaml b/lib/I18n/translations/french.yaml
index fb299ab7..0f43e82b 100644
--- a/lib/I18n/translations/french.yaml
+++ b/lib/I18n/translations/french.yaml
@@ -288,6 +288,7 @@ STR_SECTION_PREFIX: "Section "
 STR_UPLOAD: "Envoyer"
 STR_BOOK_S_STYLE: "Style du livre"
 STR_EMBEDDED_STYLE: "Style intégré"
+STR_FOCUS_READING: "Lecture focalisée"
 STR_OPDS_SERVER_URL: "URL serveur OPDS"
 STR_FOOTNOTES: "Notes de bas de page"
 STR_NO_FOOTNOTES: "Aucune note sur cette page"
diff --git a/lib/I18n/translations/german.yaml b/lib/I18n/translations/german.yaml
index 28312b81..d2f8d0e6 100644
--- a/lib/I18n/translations/german.yaml
+++ b/lib/I18n/translations/german.yaml
@@ -289,6 +289,7 @@ STR_SECTION_PREFIX: "Abschnitt"
 STR_UPLOAD: "Hochladen"
 STR_BOOK_S_STYLE: "Buch-Stil"
 STR_EMBEDDED_STYLE: "Eingebetteter Stil"
+STR_FOCUS_READING: "Fokus-Lesen"
 STR_OPDS_SERVER_URL: "OPDS-Server-URL"
 STR_SCREENSHOT_BUTTON: "Screenshot aufnehmen"
 STR_FOOTNOTES: "Fußnoten"
diff --git a/lib/I18n/translations/hungarian.yaml b/lib/I18n/translations/hungarian.yaml
index 759768aa..070f2a28 100644
--- a/lib/I18n/translations/hungarian.yaml
+++ b/lib/I18n/translations/hungarian.yaml
@@ -284,6 +284,7 @@ STR_SECTION_PREFIX: "Szakasz "
 STR_UPLOAD: "Feltöltés"
 STR_BOOK_S_STYLE: "Könyv stílusa"
 STR_EMBEDDED_STYLE: "Beágyazott stílus"
+STR_FOCUS_READING: "Fókuszált olvasás"
 STR_OPDS_SERVER_URL: "OPDS szerver URL"
 STR_FOOTNOTES: "Lábjegyzetek"
 STR_NO_FOOTNOTES: "Nincsenek lábjegyzetek ezen az oldalon"
diff --git a/lib/I18n/translations/italian.yaml b/lib/I18n/translations/italian.yaml
index 3c3bb17b..4a180b4f 100644
--- a/lib/I18n/translations/italian.yaml
+++ b/lib/I18n/translations/italian.yaml
@@ -288,6 +288,7 @@ STR_SECTION_PREFIX: "Sezione "
 STR_UPLOAD: "Carica"
 STR_BOOK_S_STYLE: "Stile libro"
 STR_EMBEDDED_STYLE: "Stile integrato dell'epub"
+STR_FOCUS_READING: "Lettura focalizzata"
 STR_OPDS_SERVER_URL: "Server OPDS"
 STR_FOOTNOTES: "Note a piè pagina"
 STR_NO_FOOTNOTES: "Nessuna nota in questa pagina"
diff --git a/lib/I18n/translations/kazakh.yaml b/lib/I18n/translations/kazakh.yaml
index fbee8021..5d9c03e9 100644
--- a/lib/I18n/translations/kazakh.yaml
+++ b/lib/I18n/translations/kazakh.yaml
@@ -258,6 +258,7 @@ STR_SECTION_PREFIX: "Бөлім "
 STR_UPLOAD: "Жүктеп салу"
 STR_BOOK_S_STYLE: "Кітап стилі"
 STR_EMBEDDED_STYLE: "Кірістірілген стиль"
+STR_FOCUS_READING: "Зейінді оқу"
 STR_OPDS_SERVER_URL: "OPDS сервері URL"
 STR_NO_FILES_FOUND: "Файлдар табылмады"
 STR_IMAGES: "Суреттер"
diff --git a/lib/I18n/translations/lithuanian.yaml b/lib/I18n/translations/lithuanian.yaml
index bae0764a..d7619a1f 100644
--- a/lib/I18n/translations/lithuanian.yaml
+++ b/lib/I18n/translations/lithuanian.yaml
@@ -284,6 +284,7 @@ STR_SECTION_PREFIX: "Dalis "
 STR_UPLOAD: "Įkelti"
 STR_BOOK_S_STYLE: "Knygos stilius"
 STR_EMBEDDED_STYLE: "Integruotas stilius"
+STR_FOCUS_READING: "Sufokusuotas skaitymas"
 STR_OPDS_SERVER_URL: "OPDS URL"
 STR_FOOTNOTES: "Išnašos"
 STR_NO_FOOTNOTES: "Šiame psl. išnašų nėra"
diff --git a/lib/I18n/translations/polish.yaml b/lib/I18n/translations/polish.yaml
index b85a8719..721dddba 100644
--- a/lib/I18n/translations/polish.yaml
+++ b/lib/I18n/translations/polish.yaml
@@ -296,6 +296,7 @@ STR_SECTION_PREFIX: "Sekcja "
 STR_UPLOAD: "Wyślij"
 STR_BOOK_S_STYLE: "Styl książki"
 STR_EMBEDDED_STYLE: "Style wbudowane w EPUB"
+STR_FOCUS_READING: "Czytanie skupione"
 STR_OPDS_SERVER_URL: "URL serwera OPDS"
 STR_SET_SLEEP_COVER: "Ustaw okładkę"
 STR_FOOTNOTES: "Przypisy"
diff --git a/lib/I18n/translations/portuguese.yaml b/lib/I18n/translations/portuguese.yaml
index e6249adb..97b447b9 100644
--- a/lib/I18n/translations/portuguese.yaml
+++ b/lib/I18n/translations/portuguese.yaml
@@ -264,6 +264,7 @@ STR_SECTION_PREFIX: "Seção"
 STR_UPLOAD: "Enviar"
 STR_BOOK_S_STYLE: "Estilo do livro"
 STR_EMBEDDED_STYLE: "Estilo embutido"
+STR_FOCUS_READING: "Leitura focada"
 STR_OPDS_SERVER_URL: "URL do servidor OPDS"
 STR_SCREENSHOT_BUTTON: "Capturar tela"
 STR_TILT_PAGE_TURN: "Virar página por inclinação"
diff --git a/lib/I18n/translations/romanian.yaml b/lib/I18n/translations/romanian.yaml
index d4e004db..84d7cac9 100644
--- a/lib/I18n/translations/romanian.yaml
+++ b/lib/I18n/translations/romanian.yaml
@@ -287,6 +287,7 @@ STR_SECTION_PREFIX: "Secţiune "
 STR_UPLOAD: "Încărcare"
 STR_BOOK_S_STYLE: "Stilul cărţii"
 STR_EMBEDDED_STYLE: "Stil încorporat"
+STR_FOCUS_READING: "Lectură concentrată"
 STR_OPDS_SERVER_URL: "URL server OPDS"
 STR_FOOTNOTES: "Note de subsol"
 STR_NO_FOOTNOTES: "Nicio notă de subsol"
diff --git a/lib/I18n/translations/russian.yaml b/lib/I18n/translations/russian.yaml
index 6f00d6c3..005a5eea 100644
--- a/lib/I18n/translations/russian.yaml
+++ b/lib/I18n/translations/russian.yaml
@@ -291,6 +291,7 @@ STR_SECTION_PREFIX: "Раздел "
 STR_UPLOAD: "Отправить"
 STR_BOOK_S_STYLE: "Стиль книги"
 STR_EMBEDDED_STYLE: "Встроенный стиль"
+STR_FOCUS_READING: "Фокусное чтение"
 STR_OPDS_SERVER_URL: "URL OPDS сервера"
 STR_SCREENSHOT_BUTTON: "Сделать снимок экрана"
 STR_AUTO_TURN_ENABLED: "Автоперелистывание: "
diff --git a/lib/I18n/translations/slovenian.yaml b/lib/I18n/translations/slovenian.yaml
index 20103772..7e506661 100644
--- a/lib/I18n/translations/slovenian.yaml
+++ b/lib/I18n/translations/slovenian.yaml
@@ -284,6 +284,7 @@ STR_SECTION_PREFIX: "Razdelek "
 STR_UPLOAD: "Naloži"
 STR_BOOK_S_STYLE: "Slog knjige"
 STR_EMBEDDED_STYLE: "Vgrajen slog"
+STR_FOCUS_READING: "Fokusirano branje"
 STR_OPDS_SERVER_URL: "URL OPDS strežnika"
 STR_FOOTNOTES: "Opombe"
 STR_NO_FOOTNOTES: "Na tej strani ni opomb"
diff --git a/lib/I18n/translations/spanish.yaml b/lib/I18n/translations/spanish.yaml
index ea2e56dc..9b4af843 100644
--- a/lib/I18n/translations/spanish.yaml
+++ b/lib/I18n/translations/spanish.yaml
@@ -288,6 +288,7 @@ STR_SECTION_PREFIX: "Secc.:"
 STR_UPLOAD: "Subir"
 STR_BOOK_S_STYLE: "Estilo del libro"
 STR_EMBEDDED_STYLE: "Estilo integrado"
+STR_FOCUS_READING: "Lectura enfocada"
 STR_OPDS_SERVER_URL: "URL del servidor OPDS"
 STR_FOOTNOTES: "Pie de página"
 STR_NO_FOOTNOTES: "No hay notas al pie de esta página"
diff --git a/lib/I18n/translations/swedish.yaml b/lib/I18n/translations/swedish.yaml
index 84ac108e..3ab175c5 100644
--- a/lib/I18n/translations/swedish.yaml
+++ b/lib/I18n/translations/swedish.yaml
@@ -296,6 +296,7 @@ STR_SECTION_PREFIX: "Sektion"
 STR_UPLOAD: "Uppladdning"
 STR_BOOK_S_STYLE: "Bokstil"
 STR_EMBEDDED_STYLE: "Inbäddad stil"
+STR_FOCUS_READING: "Fokusläsning"
 STR_OPDS_SERVER_URL: "OPDS-serveradress"
 STR_SET_SLEEP_COVER: "Ställ in omslag"
 STR_FOOTNOTES: "Fotnoter"
diff --git a/lib/I18n/translations/turkish.yaml b/lib/I18n/translations/turkish.yaml
index 066af673..6e0784ce 100644
--- a/lib/I18n/translations/turkish.yaml
+++ b/lib/I18n/translations/turkish.yaml
@@ -262,6 +262,7 @@ STR_SECTION_PREFIX: "Bölüm "
 STR_UPLOAD: "Yükle"
 STR_BOOK_S_STYLE: "Kitabın Stili"
 STR_EMBEDDED_STYLE: "Gömülü Stil"
+STR_FOCUS_READING: "Odaklanmış Okuma"
 STR_OPDS_SERVER_URL: "OPDS Sunucu Adresi"
 STR_AUTO_TURN_ENABLED: "Otomatik Çevirme Etkin: "
 STR_AUTO_TURN_PAGES_PER_MIN: "Otomatik Çevirme (Dakikada Sayfa)"
diff --git a/lib/I18n/translations/ukrainian.yaml b/lib/I18n/translations/ukrainian.yaml
index dfe0d019..dc286ffd 100644
--- a/lib/I18n/translations/ukrainian.yaml
+++ b/lib/I18n/translations/ukrainian.yaml
@@ -292,6 +292,7 @@ STR_SECTION_PREFIX: "Розділ "
 STR_UPLOAD: "Завантажити"
 STR_BOOK_S_STYLE: "Стиль книги"
 STR_EMBEDDED_STYLE: "Вбудований стиль"
+STR_FOCUS_READING: "Фокусне читання"
 STR_OPDS_SERVER_URL: "URL сервера OPDS"
 STR_FOOTNOTES: "Примітки"
 STR_NO_FOOTNOTES: "На цій сторінці немає приміток"
diff --git a/open-x4-sdk b/open-x4-sdk
index 7d86603a..a64a3c29 160000
--- a/open-x4-sdk
+++ b/open-x4-sdk
@@ -1 +1 @@
-Subproject commit 7d86603ad27709a9a766bb5ad893cfc39e60777e
+Subproject commit a64a3c29bebc59b2ccdfe15492cfc4b5e4c26360
diff --git a/src/CrossPointSettings.h b/src/CrossPointSettings.h
index bd6a8502..0b769005 100644
--- a/src/CrossPointSettings.h
+++ b/src/CrossPointSettings.h
@@ -213,6 +213,8 @@ class CrossPointSettings {
   uint8_t fadingFix = 0;
   // Use book's embedded CSS styles for EPUB rendering (1 = enabled, 0 = disabled)
   uint8_t embeddedStyle = 1;
+  // Focus Reading - emphasizes the first part of words with bold
+  uint8_t focusReadingEnabled = 0;
   // SD card font family name (empty = use built-in fontFamily)
   char sdFontFamilyName[32] = "";
   // Show hidden files/directories (starting with '.') in the file browser (0 = hidden, 1 = show)
diff --git a/src/SettingsList.h b/src/SettingsList.h
index 9af7101e..d8a118c3 100644
--- a/src/SettingsList.h
+++ b/src/SettingsList.h
@@ -145,6 +145,8 @@ inline std::vector<SettingInfo> getSettingsList(const SdCardFontRegistry* regist
                           "paragraphAlignment", StrId::STR_CAT_READER),
         SettingInfo::Toggle(StrId::STR_EMBEDDED_STYLE, &CrossPointSettings::embeddedStyle, "embeddedStyle",
                             StrId::STR_CAT_READER),
+        SettingInfo::Toggle(StrId::STR_FOCUS_READING, &CrossPointSettings::focusReadingEnabled, "focusReadingEnabled",
+                            StrId::STR_CAT_READER),
         SettingInfo::Toggle(StrId::STR_HYPHENATION, &CrossPointSettings::hyphenationEnabled, "hyphenationEnabled",
                             StrId::STR_CAT_READER),
         SettingInfo::Enum(StrId::STR_ORIENTATION, &CrossPointSettings::orientation,
diff --git a/src/activities/reader/EpubReaderActivity.cpp b/src/activities/reader/EpubReaderActivity.cpp
index 3de6d69d..7732762b 100644
--- a/src/activities/reader/EpubReaderActivity.cpp
+++ b/src/activities/reader/EpubReaderActivity.cpp
@@ -609,7 +609,7 @@ void EpubReaderActivity::render(RenderLock&& lock) {
     if (!section->loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                   SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                   viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle,
-                                  SETTINGS.imageRendering)) {
+                                  SETTINGS.imageRendering, SETTINGS.focusReadingEnabled)) {
       LOG_DBG("ERS", "Cache not found, building...");
 
       GUI.drawPopup(renderer, tr(STR_INDEXING));
@@ -619,7 +619,7 @@ void EpubReaderActivity::render(RenderLock&& lock) {
       if (!section->createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                       SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                       viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle,
-                                      SETTINGS.imageRendering, popupFn)) {
+                                      SETTINGS.imageRendering, SETTINGS.focusReadingEnabled, popupFn)) {
         LOG_ERR("ERS", "Failed to persist page data to SD");
         section.reset();
         showPendingSyncSaveError();
@@ -750,7 +750,7 @@ void EpubReaderActivity::silentIndexNextChapterIfNeeded(const uint16_t viewportW
   if (nextSection.loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                   SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                   viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle,
-                                  SETTINGS.imageRendering)) {
+                                  SETTINGS.imageRendering, SETTINGS.focusReadingEnabled)) {
     return;
   }
 
@@ -758,7 +758,7 @@ void EpubReaderActivity::silentIndexNextChapterIfNeeded(const uint16_t viewportW
   if (!nextSection.createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                      SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                      viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle,
-                                     SETTINGS.imageRendering)) {
+                                     SETTINGS.imageRendering, SETTINGS.focusReadingEnabled)) {
     LOG_ERR("ERS", "Failed silent indexing for chapter: %d", nextSpineIndex);
   }
 }