feat: add configurable reading font using Bunny Fonts

- Add readingFont setting to UserSettings interface
- Create fontLoader utility to load fonts from Bunny Fonts
- Add font selector dropdown in settings with popular reading fonts
- Use CSS variable --reading-font to apply font to reader content
- Support fonts: Inter, Lora, Merriweather, Open Sans, Roboto, Source Serif 4, Crimson Text, Libre Baskerville, PT Serif
- Fonts loaded from https://fonts.bunny.net/ (GDPR-friendly)

src/components/Bookmarks.tsx

@@ -13,6 +13,7 @@ import { HighlightsPanel } from './HighlightsPanel'
 import { fetchReadableContent, ReadableContent } from '../services/readerService'
 import Settings from './Settings'
 import { UserSettings, loadSettings, saveSettings } from '../services/settingsService'
+import { loadFont, getFontFamily } from '../utils/fontLoader'
 
 export type ViewMode = 'compact' | 'cards' | 'large'
 
@@ -65,6 +66,12 @@ const Bookmarks: React.FC<BookmarksProps> = ({ relayPool, onLogout }) => {
     if (settings.showUnderlines !== undefined) setShowUnderlines(settings.showUnderlines)
     if (settings.sidebarCollapsed !== undefined) setIsCollapsed(settings.sidebarCollapsed)
     if (settings.highlightsCollapsed !== undefined) setIsHighlightsCollapsed(settings.highlightsCollapsed)
+    if (settings.readingFont) {
+      loadFont(settings.readingFont)
+      // Apply font to content panel
+      const fontFamily = getFontFamily(settings.readingFont)
+      document.documentElement.style.setProperty('--reading-font', fontFamily)
+    }
   }, [settings])
 
   const handleFetchBookmarks = async () => {

src/components/Settings.tsx

@@ -76,6 +76,27 @@ const Settings: React.FC<SettingsProps> = ({ settings, onSave, onClose, isSaving
             </div>
           </div>
 
+          <div className="setting-group">
+            <label htmlFor="readingFont">Reading Font</label>
+            <select
+              id="readingFont"
+              value={localSettings.readingFont || 'system'}
+              onChange={(e) => setLocalSettings({ ...localSettings, readingFont: e.target.value })}
+              className="setting-select"
+            >
+              <option value="system">System Default</option>
+              <option value="inter">Inter</option>
+              <option value="lora">Lora</option>
+              <option value="merriweather">Merriweather</option>
+              <option value="open-sans">Open Sans</option>
+              <option value="roboto">Roboto</option>
+              <option value="source-serif-4">Source Serif 4</option>
+              <option value="crimson-text">Crimson Text</option>
+              <option value="libre-baskerville">Libre Baskerville</option>
+              <option value="pt-serif">PT Serif</option>
+            </select>
+          </div>
+
           <div className="setting-group">
             <label htmlFor="showUnderlines" className="checkbox-label">
               <input

src/index.css

@@ -12,6 +12,8 @@
   -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;
   -webkit-text-size-adjust: 100%;
+  
+  --reading-font: system-ui, -apple-system, sans-serif;
 }
 
 body {
@@ -524,11 +526,13 @@ body {
   word-wrap: break-word;
   overflow-wrap: break-word;
   word-break: break-word;
+  font-family: var(--reading-font);
 }
 
 .reader-markdown {
   color: #ddd;
   line-height: 1.7;
+  font-family: var(--reading-font);
 }
 
 /* Ensure content is left-aligned even if source markup uses center */

src/services/settingsService.ts

@@ -14,6 +14,7 @@ export interface UserSettings {
   showUnderlines?: boolean
   sidebarCollapsed?: boolean
   highlightsCollapsed?: boolean
+  readingFont?: string
 }
 
 export async function loadSettings(

src/utils/fontLoader.ts

@@ -0,0 +1,43 @@
+// Map of font names to their Bunny Fonts family names
+const FONT_FAMILIES: Record<string, string> = {
+  'inter': 'Inter',
+  'lora': 'Lora',
+  'merriweather': 'Merriweather',
+  'open-sans': 'Open Sans',
+  'roboto': 'Roboto',
+  'source-serif-4': 'Source Serif 4',
+  'crimson-text': 'Crimson Text',
+  'libre-baskerville': 'Libre Baskerville',
+  'pt-serif': 'PT Serif'
+}
+
+const loadedFonts = new Set<string>()
+
+export function loadFont(fontKey: string) {
+  if (fontKey === 'system' || loadedFonts.has(fontKey)) {
+    return
+  }
+
+  const fontFamily = FONT_FAMILIES[fontKey]
+  if (!fontFamily) {
+    console.warn(`Unknown font: ${fontKey}`)
+    return
+  }
+
+  // Create a link element to load the font from Bunny Fonts
+  const link = document.createElement('link')
+  link.rel = 'stylesheet'
+  link.href = `https://fonts.bunny.net/css?family=${encodeURIComponent(fontFamily.toLowerCase().replace(/ /g, '-'))}:400,400i,700,700i`
+  document.head.appendChild(link)
+
+  loadedFonts.add(fontKey)
+}
+
+export function getFontFamily(fontKey: string | undefined): string {
+  if (!fontKey || fontKey === 'system') {
+    return 'system-ui, -apple-system, sans-serif'
+  }
+
+  const fontFamily = FONT_FAMILIES[fontKey]
+  return fontFamily ? `'${fontFamily}', serif` : 'system-ui, -apple-system, sans-serif'
+}