diff --git a/static/css/app.css b/static/css/app.css
index 5b200a9..fd2bcc6 100644
--- a/static/css/app.css
+++ b/static/css/app.css
@@ -2130,7 +2130,7 @@ body.reader-immersive.reader-show-bottom .reader-overlay  { bottom: var(--bar-h)
 .footnote-popover-close { position:absolute; top:4px; right:6px; background:none; border:none; color:inherit; opacity:0.5; cursor:pointer; font-size:14px; padding:2px 4px; line-height:1; }
 
 /* Highlight marks */
-.reader-no-bold * { font-weight: normal !important; }
+.reader-no-bold * { font-weight: inherit !important; }
 .reader-content img { max-width: 100%; height: auto; display: block; }
 /* color:inherit overrides the browser's UA-default `mark { color: black }` —
    without it, highlighted text abruptly flips to black regardless of the
diff --git a/static/js/app.js b/static/js/app.js
index 64a27d3..cf513db 100644
--- a/static/js/app.js
+++ b/static/js/app.js
@@ -3254,7 +3254,7 @@ async function _syncPendingAnnotations() {
 
 // Reader settings
 let readerSettings = { fontSize: 16, lineHeight: 1.8, maxWidth: 65, theme: 'dark',
-                        fontFamily: 'serif', noBold: false,
+                        fontFamily: 'serif', noBold: false, fontWeight: null,
                         pdfZoom: 100, pdfInverted: false, pdfPaginated: false, pdfSpread: false };
 let readerSettingsPanelOpen = false;
 let currentPdfDoc = null;
@@ -5026,7 +5026,7 @@ function jumpToTocEntry(href) {
 function loadReaderSettings(bookId) {
   // Reset to defaults, then apply per-book overrides
   Object.assign(readerSettings, { fontSize: 16, lineHeight: 1.8, maxWidth: 65, theme: 'dark',
-                                   fontFamily: 'serif', noBold: false,
+                                   fontFamily: 'serif', noBold: false, fontWeight: null,
                                    pdfZoom: 100, pdfInverted: false, pdfPaginated: false, pdfSpread: false });
   try {
     const saved = JSON.parse(localStorage.getItem(`diora_reader_settings_${bookId}`) || '{}');
@@ -5060,6 +5060,16 @@ function applyReaderSettings(isPdf) {
     };
     contentEl.style.fontFamily = fontMap[readerSettings.fontFamily] || fontMap.serif;
     contentEl.classList.toggle('reader-no-bold', !!readerSettings.noBold);
+    // Weight: null keeps the stylesheet's. --reader-weight lets old WebViews
+    // without variable-font support (which drop weights like 425) pick a
+    // static cut instead.
+    contentEl.style.fontWeight = '';
+    if (readerSettings.fontWeight) {
+      contentEl.style.fontWeight = String(readerSettings.fontWeight);
+      contentEl.style.setProperty('--reader-weight', String(readerSettings.fontWeight));
+    } else {
+      contentEl.style.removeProperty('--reader-weight');
+    }
     if (_currentPositionAnchor && currentBookId) {
       _suppressScrollJumpDetect();
       requestAnimationFrame(() => restoreFromAnchor($('reader-content'), _currentPositionAnchor));
@@ -5083,6 +5093,19 @@ function applyReaderSettings(isPdf) {
   if (isPdf && markerModeActive) toggleMarkerMode();
 }
 
+// Font weight slider: the variable Source Serif 4 takes any weight, the
+// system fonts only their fixed cuts (multiples of 100).
+function _readerWeightStep() {
+  return readerSettings.fontFamily === 'serif' ? 25 : 100;
+}
+
+function _readerWeight() {
+  const step = _readerWeightStep();
+  const w = readerSettings.fontWeight
+    || parseInt(getComputedStyle($('reader-content')).fontWeight, 10) || 400;
+  return Math.round(w / step) * step;
+}
+
 function toggleSettingsPanel() {
   const overlay = $('reader-overlay');
   const contentEl = $('reader-content');
@@ -5108,6 +5131,7 @@ function toggleSettingsPanel() {
       <label>Line <button class="btn btn-sm" id="rs-line-minus">−</button> <input type="range" id="rs-line" min="12" max="30" step="1" value="${Math.round(readerSettings.lineHeight * 10)}"> <button class="btn btn-sm" id="rs-line-plus">+</button> <span id="rs-line-val">${readerSettings.lineHeight}</span></label>
       <label>Width <button class="btn btn-sm" id="rs-width-minus">−</button> <input type="range" id="rs-width" min="40" max="90" step="5" value="${readerSettings.maxWidth}"> <button class="btn btn-sm" id="rs-width-plus">+</button> <span id="rs-width-val">${readerSettings.maxWidth}ch</span></label>
       <button class="btn btn-sm" id="rs-width-full">Full</button>
+      <label>Weight <button class="btn btn-sm" id="rs-weight-minus">−</button> <input type="range" id="rs-weight" min="200" max="800" step="${_readerWeightStep()}" value="${_readerWeight()}"> <button class="btn btn-sm" id="rs-weight-plus">+</button> <span id="rs-weight-val">${_readerWeight()}</span></label>
       <button class="btn btn-sm ${readerSettings.fontFamily === 'serif'    ? 'active' : ''}" data-rs-font="serif">Serif</button>
       <button class="btn btn-sm ${readerSettings.fontFamily === 'sans'     ? 'active' : ''}" data-rs-font="sans">Sans</button>
       <button class="btn btn-sm ${readerSettings.fontFamily === 'humanist' ? 'active' : ''}" data-rs-font="humanist">Verdana</button>
@@ -5187,12 +5211,36 @@ function toggleSettingsPanel() {
       saveReaderSettings();
     });
 
+    const weightRange = panel.querySelector('#rs-weight');
+    const weightVal   = panel.querySelector('#rs-weight-val');
+    weightRange.addEventListener('input', () => {
+      readerSettings.fontWeight = parseInt(weightRange.value, 10);
+      weightVal.textContent = readerSettings.fontWeight;
+      applyReaderSettings(false);
+      saveReaderSettings();
+    });
+    panel.querySelector('#rs-weight-minus').addEventListener('click', () => {
+      weightRange.value = Math.max(+weightRange.min, parseInt(weightRange.value, 10) - +weightRange.step);
+      weightRange.dispatchEvent(new Event('input'));
+    });
+    panel.querySelector('#rs-weight-plus').addEventListener('click', () => {
+      weightRange.value = Math.min(+weightRange.max, parseInt(weightRange.value, 10) + +weightRange.step);
+      weightRange.dispatchEvent(new Event('input'));
+    });
+
     panel.querySelectorAll('[data-rs-font]').forEach(btn => {
       btn.addEventListener('click', () => {
         readerSettings.fontFamily = btn.dataset.rsFont;
         panel.querySelectorAll('[data-rs-font]').forEach(b => b.classList.toggle('active', b === btn));
+        // The system fonts only have cuts at multiples of 100.
+        weightRange.step = _readerWeightStep();
+        if (readerSettings.fontWeight) {
+          readerSettings.fontWeight = Math.round(readerSettings.fontWeight / weightRange.step) * weightRange.step;
+        }
         applyReaderSettings(false);
         saveReaderSettings();
+        weightRange.value = _readerWeight();
+        weightVal.textContent = _readerWeight();
       });
     });
 
diff --git a/static/js/sw.js b/static/js/sw.js
index 24a7b9c..2b72b57 100644
--- a/static/js/sw.js
+++ b/static/js/sw.js
@@ -2,7 +2,7 @@
  * diora service worker — caches the app shell for offline use.
  */
 
-const CACHE = 'diora-v46';
+const CACHE = 'diora-v47';
 const PODCAST_CACHE = 'diora-podcast-v1';
 const SHELL = [
   '/static/css/app.css',