diff --git a/frontend/app.js b/frontend/app.js
index fda8b46..f36450e 100644
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -11,6 +11,22 @@ const CONFIG = {
     DEFAULT_SIDEBAR_WIDTH: 256,        // px - Default sidebar width (w-64 in Tailwind)
 };
 
+// localStorage settings configuration - centralized definition of all persisted settings
+const LOCAL_SETTINGS = {
+    // Boolean settings
+    syntaxHighlightEnabled: { key: 'syntaxHighlightEnabled', type: 'boolean', default: false },
+    readableLineLength: { key: 'readableLineLength', type: 'boolean', default: true },
+    favoritesExpanded: { key: 'favoritesExpanded', type: 'boolean', default: true },
+    tagsExpanded: { key: 'tagsExpanded', type: 'boolean', default: false },
+    // Number settings with validation
+    sidebarWidth: { key: 'sidebarWidth', type: 'number', default: CONFIG.DEFAULT_SIDEBAR_WIDTH, min: 200, max: 600 },
+    editorWidth: { key: 'editorWidth', type: 'number', default: 50, min: 20, max: 80 },
+    // String settings with validation
+    viewMode: { key: 'viewMode', type: 'string', default: 'split', valid: ['edit', 'split', 'preview'] },
+    // JSON settings
+    favorites: { key: 'noteFavorites', type: 'json', default: [] },
+};
+
 // Centralized error handling
 const ErrorHandler = {
     /**
@@ -190,6 +206,9 @@ function noteApp() {
         syntaxHighlightEnabled: false,
         syntaxHighlightTimeout: null,
         
+        // Readable line length (preview max-width)
+        readableLineLength: true,
+        
         // Icon rail / panel state
         activePanel: 'files', // 'files', 'search', 'tags', 'settings'
         
@@ -458,13 +477,7 @@ function noteApp() {
             await this.loadSharedNotePaths();
             await this.loadTemplates();
             await this.checkStatsPlugin();
-            this.loadSidebarWidth();
-            this.loadEditorWidth();
-            this.loadViewMode();
-            this.loadTagsExpanded();
-            this.loadFavorites();
-            this.loadFavoritesExpanded();
-            this.loadSyntaxHighlightSetting();
+            this.loadLocalSettings();
             
             // Parse URL and load specific note if provided
             this.loadItemFromURL();
@@ -745,13 +758,51 @@ function noteApp() {
             }
         },
         
-        loadSyntaxHighlightSetting() {
-            try {
-                const saved = localStorage.getItem('syntaxHighlightEnabled');
-                this.syntaxHighlightEnabled = saved === 'true';
-            } catch (error) {
-                console.error('Error loading syntax highlight setting:', error);
+        // Load all localStorage settings at once using centralized config
+        loadLocalSettings() {
+            for (const [prop, config] of Object.entries(LOCAL_SETTINGS)) {
+                try {
+                    const saved = localStorage.getItem(config.key);
+                    
+                    if (saved === null) {
+                        // Use default value if not set
+                        this[prop] = config.default;
+                    } else if (config.type === 'boolean') {
+                        this[prop] = saved === 'true';
+                    } else if (config.type === 'number') {
+                        const num = parseFloat(saved);
+                        // Validate range if specified
+                        if (!isNaN(num) && 
+                            (config.min === undefined || num >= config.min) && 
+                            (config.max === undefined || num <= config.max)) {
+                            this[prop] = num;
+                        } else {
+                            this[prop] = config.default;
+                        }
+                    } else if (config.type === 'string') {
+                        // Validate against allowed values if specified
+                        if (!config.valid || config.valid.includes(saved)) {
+                            this[prop] = saved;
+                        } else {
+                            this[prop] = config.default;
+                        }
+                    } else if (config.type === 'json') {
+                        this[prop] = JSON.parse(saved);
+                    }
+                } catch (error) {
+                    console.error(`Error loading setting ${prop}:`, error);
+                    this[prop] = config.default;
+                }
             }
+            
+            // Special case: favorites also needs to update the Set for O(1) lookups
+            this.favoritesSet = new Set(this.favorites);
+        },
+        
+        // Readable line length toggle (for preview max-width)
+        toggleReadableLineLength() {
+            this.readableLineLength = !this.readableLineLength;
+            localStorage.setItem('readableLineLength', this.readableLineLength);
         },
         
         // Update syntax highlight overlay (debounced, called on input)
@@ -1439,20 +1490,6 @@ function noteApp() {
         
         // ==================== FAVORITES ====================
         
-        // Load favorites from localStorage
-        loadFavorites() {
-            try {
-                const stored = localStorage.getItem('noteFavorites');
-                if (stored) {
-                    this.favorites = JSON.parse(stored);
-                    this.favoritesSet = new Set(this.favorites);
-                }
-            } catch (e) {
-                this.favorites = [];
-                this.favoritesSet = new Set();
-            }
-        },
-        
         // Save favorites to localStorage
         saveFavorites() {
             try {
@@ -1503,17 +1540,6 @@ function noteApp() {
                 .filter(Boolean); // Remove nulls (deleted notes)
         },
         
-        loadFavoritesExpanded() {
-            try {
-                const saved = localStorage.getItem('favoritesExpanded');
-                if (saved !== null) {
-                    this.favoritesExpanded = saved === 'true';
-                }
-            } catch (e) {
-                console.error('Error loading favorites expanded state:', e);
-            }
-        },
-        
         saveFavoritesExpanded() {
             try {
                 localStorage.setItem('favoritesExpanded', this.favoritesExpanded.toString());
@@ -4770,34 +4796,11 @@ function noteApp() {
             return Array.isArray(this.noteMetadata.tags) ? this.noteMetadata.tags : [this.noteMetadata.tags];
         },
         
-        // Load sidebar width from localStorage
-        loadSidebarWidth() {
-            const saved = localStorage.getItem('sidebarWidth');
-            if (saved) {
-                const width = parseInt(saved, 10);
-                if (width >= 200 && width <= 600) {
-                    this.sidebarWidth = width;
-                }
-            }
-        },
-        
         // Save sidebar width to localStorage
         saveSidebarWidth() {
             localStorage.setItem('sidebarWidth', this.sidebarWidth.toString());
         },
         
-        // Load view mode from localStorage
-        loadViewMode() {
-            try {
-                const saved = localStorage.getItem('viewMode');
-                if (saved && ['edit', 'split', 'preview'].includes(saved)) {
-                    this.viewMode = saved;
-                }
-            } catch (error) {
-                console.error('Error loading view mode:', error);
-            }
-        },
-        
         // Save view mode to localStorage
         saveViewMode() {
             try {
@@ -4807,17 +4810,6 @@ function noteApp() {
             }
         },
         
-        loadTagsExpanded() {
-            try {
-                const saved = localStorage.getItem('tagsExpanded');
-                if (saved !== null) {
-                    this.tagsExpanded = saved === 'true';
-                }
-            } catch (error) {
-                console.error('Error loading tags expanded state:', error);
-            }
-        },
-        
         saveTagsExpanded() {
             try {
                 localStorage.setItem('tagsExpanded', this.tagsExpanded.toString());
@@ -4916,17 +4908,6 @@ function noteApp() {
             }
         },
         
-        // Load editor width from localStorage
-        loadEditorWidth() {
-            const saved = localStorage.getItem('editorWidth');
-            if (saved) {
-                const width = parseFloat(saved);
-                if (width >= 20 && width <= 80) {
-                    this.editorWidth = width;
-                }
-            }
-        },
-        
         // Save editor width to localStorage
         saveEditorWidth() {
             localStorage.setItem('editorWidth', this.editorWidth.toString());
diff --git a/frontend/index.html b/frontend/index.html
index f915c1c..0f0ea01 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -170,6 +170,13 @@
             font-size: 16px;
         }
         
+        /* Readable line length - constrain text width for better readability */
+        .markdown-preview.readable-width {
+            max-width: 750px;
+            margin-left: auto;
+            margin-right: auto;
+        }
+        
         /* Remove top margin from first element */
         .markdown-preview > *:first-child {
             margin-top: 0 !important;
@@ -1829,6 +1836,24 @@
                                     <p class="text-xs mt-1" style="color: var(--text-tertiary);" x-text="t('syntax_highlight.description')"></p>
                                 </div>
                                 
+                                <!-- Readable Line Length Toggle -->
+                                <div class="mb-4">
+                                    <label class="flex items-center justify-between cursor-pointer">
+                                        <span class="text-xs font-medium" style="color: var(--text-secondary);" x-text="t('settings.readable_line_length')"></span>
+                                        <div 
+                                            @click="toggleReadableLineLength()"
+                                            class="relative w-10 h-5 rounded-full transition-colors cursor-pointer"
+                                            :style="readableLineLength ? 'background-color: var(--accent-primary)' : 'background-color: var(--bg-tertiary)'"
+                                        >
+                                            <div 
+                                                class="absolute top-0.5 left-0.5 w-4 h-4 rounded-full transition-transform"
+                                                :style="'background-color: var(--bg-primary);' + (readableLineLength ? ' transform: translateX(20px);' : '')"
+                                            ></div>
+                                        </div>
+                                    </label>
+                                    <p class="text-xs mt-1" style="color: var(--text-tertiary);" x-text="t('settings.readable_line_length_desc')"></p>
+                                </div>
+                                
                                 <!-- Logout (if auth enabled) - uses authEnabled from main app state -->
                                 <div x-show="authEnabled" class="mb-4">
                                     <label class="block text-xs font-medium mb-2" style="color: var(--text-secondary);" x-text="t('settings.account')"></label>
@@ -2576,7 +2601,7 @@
                             
                             <div 
                                 class="p-6 markdown-preview"
-                                :class="{ 'pt-2': getHasMetadata() && currentNote }"
+                                :class="{ 'pt-2': getHasMetadata() && currentNote, 'readable-width': readableLineLength }"
                                 x-html="renderedMarkdown"
                                 @click="handleInternalLink($event)"
                             ></div>
diff --git a/locales/de-DE.json b/locales/de-DE.json
index c1c89f6..d1ee9c8 100644
--- a/locales/de-DE.json
+++ b/locales/de-DE.json
@@ -235,7 +235,9 @@
 
   "settings": {
     "account": "Konto",
-    "logout": "Abmelden"
+    "logout": "Abmelden",
+    "readable_line_length": "Lesbare Zeilenlänge",
+    "readable_line_length_desc": "Vorschaubreite für bessere Lesbarkeit begrenzen"
   },
 
   "homepage": {
diff --git a/locales/en-GB.json b/locales/en-GB.json
index 72317dd..40ec7c0 100644
--- a/locales/en-GB.json
+++ b/locales/en-GB.json
@@ -234,7 +234,9 @@
 
   "settings": {
     "account": "Account",
-    "logout": "Logout"
+    "logout": "Logout",
+    "readable_line_length": "Readable line length",
+    "readable_line_length_desc": "Limit preview width for easier reading"
   },
 
   "homepage": {
diff --git a/locales/en-US.json b/locales/en-US.json
index a691505..303881f 100644
--- a/locales/en-US.json
+++ b/locales/en-US.json
@@ -235,7 +235,9 @@
 
   "settings": {
     "account": "Account",
-    "logout": "Logout"
+    "logout": "Logout",
+    "readable_line_length": "Readable line length",
+    "readable_line_length_desc": "Limit preview width for easier reading"
   },
 
   "homepage": {
diff --git a/locales/es-ES.json b/locales/es-ES.json
index e0d10f6..193ca8e 100644
--- a/locales/es-ES.json
+++ b/locales/es-ES.json
@@ -235,7 +235,9 @@
 
   "settings": {
     "account": "Cuenta",
-    "logout": "Cerrar sesión"
+    "logout": "Cerrar sesión",
+    "readable_line_length": "Longitud de línea legible",
+    "readable_line_length_desc": "Limitar el ancho de vista previa para facilitar la lectura"
   },
 
   "homepage": {
diff --git a/locales/fr-FR.json b/locales/fr-FR.json
index 690261c..08914c7 100644
--- a/locales/fr-FR.json
+++ b/locales/fr-FR.json
@@ -235,7 +235,9 @@
 
   "settings": {
     "account": "Compte",
-    "logout": "Déconnexion"
+    "logout": "Déconnexion",
+    "readable_line_length": "Longueur de ligne lisible",
+    "readable_line_length_desc": "Limiter la largeur de l'aperçu pour une lecture plus facile"
   },
 
   "homepage": {
diff --git a/locales/it-IT.json b/locales/it-IT.json
index ccb67c2..93cbb7c 100644
--- a/locales/it-IT.json
+++ b/locales/it-IT.json
@@ -234,7 +234,9 @@
 
   "settings": {
     "account": "Account",
-    "logout": "Esci"
+    "logout": "Esci",
+    "readable_line_length": "Larghezza riga leggibile",
+    "readable_line_length_desc": "Limita la larghezza dell'anteprima per una lettura più facile"
   },
 
   "homepage": {
diff --git a/locales/ja-JP.json b/locales/ja-JP.json
index 504c034..bcb34d6 100644
--- a/locales/ja-JP.json
+++ b/locales/ja-JP.json
@@ -234,7 +234,9 @@
 
   "settings": {
     "account": "アカウント",
-    "logout": "ログアウト"
+    "logout": "ログアウト",
+    "readable_line_length": "読みやすい行幅",
+    "readable_line_length_desc": "プレビューの幅を制限して読みやすくする"
   },
 
   "homepage": {
diff --git a/locales/ru-RU.json b/locales/ru-RU.json
index 380def7..85b8b2c 100644
--- a/locales/ru-RU.json
+++ b/locales/ru-RU.json
@@ -234,7 +234,9 @@
 
   "settings": {
     "account": "Аккаунт",
-    "logout": "Выйти"
+    "logout": "Выйти",
+    "readable_line_length": "Удобная длина строки",
+    "readable_line_length_desc": "Ограничить ширину предпросмотра для удобства чтения"
   },
 
   "homepage": {
diff --git a/locales/sl-SI.json b/locales/sl-SI.json
index be25f2b..3a7f9a8 100644
--- a/locales/sl-SI.json
+++ b/locales/sl-SI.json
@@ -234,7 +234,9 @@
 
   "settings": {
     "account": "Račun",
-    "logout": "Odjava"
+    "logout": "Odjava",
+    "readable_line_length": "Berljiva dolžina vrstice",
+    "readable_line_length_desc": "Omejite širino predogleda za lažje branje"
   },
 
   "homepage": {
diff --git a/locales/zh-CN.json b/locales/zh-CN.json
index 82954b8..5f4b4bf 100644
--- a/locales/zh-CN.json
+++ b/locales/zh-CN.json
@@ -234,7 +234,9 @@
 
   "settings": {
     "account": "账户",
-    "logout": "登出"
+    "logout": "登出",
+    "readable_line_length": "可读行宽",
+    "readable_line_length_desc": "限制预览宽度以便于阅读"
   },
 
   "homepage": {