feat(reader): add light/dark mode toggle for reading themes

Add explicit light/dark mode toggle switch to the reading theme settings.
The reading mode defaults based on the chrome theme (dark chrome themes
like tokyo-night default to dark reading mode).

- Add readingMode property to readerShell Alpine component
- Add toggleReadingMode() method that toggles dark class on body
- Add detectChromeDarkMode() to infer default from chrome theme
- Update applyTheme() to add/remove dark class and persist reading_mode
- Add toggle switch UI in settings panel (blue pill style, next to
  Reading Theme heading)
- Add reading_mode to default settings in settings-manager

templates/reader.templ

@@ -186,7 +186,21 @@ templ ReaderSettingsPanel() {
 			</div>
 			<!-- Reading Theme (reflowable only) -->
 			<div class="mb-6" x-show="!isFixedLayout">
-				<h3 class="font-semibold mb-2">Reading Theme</h3>
+				<div class="flex items-center justify-between mb-2">
+					<h3 class="font-semibold">Reading Theme</h3>
+					<button
+						@click="toggleReadingMode()"
+						class="relative w-12 h-6 rounded-full transition-colors duration-200"
+						:class="readingMode === 'dark' ? 'bg-blue-500' : 'bg-gray-400'"
+						type="button"
+						:aria-label="readingMode === 'dark' ? 'Switch to light mode' : 'Switch to dark mode'"
+					>
+						<span
+							class="absolute top-0.5 left-0.5 w-5 h-5 bg-white rounded-full shadow transition-transform duration-200"
+							:class="readingMode === 'dark' ? 'translate-x-6' : 'translate-x-0'"
+						></span>
+					</button>
+				</div>
 				<label class="block mb-2">
 					<select name="reading_theme" x-model="readingTheme" @change="applyTheme()" class="w-full mt-1 px-3 py-2 rounded border">
 						<optgroup label="📖 Classic Reading">

templates/reader_templ.go

@@ -189,7 +189,7 @@ func ReaderSettingsPanel() templ.Component {
 			templ_7745c5c3_Var7 = templ.NopComponent
 		}
 		ctx = templ.ClearChildren(ctx)
-		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 13, "<div class=\"dockable-panel\" data-panel=\"settings\" data-side=\"left\" x-ref=\"settingsPanel\"><div class=\"panel-header flex items-center justify-between p-3 cursor-pointer\" @click=\"toggleWindowShade($refs.settingsPanel)\"><h3 class=\"panel-title font-semibold\">⚙️ Settings</h3><div class=\"panel-controls flex items-center gap-2\"><button class=\"window-shade-toggle\">─</button></div></div><div class=\"panel-content p-4 overflow-y-auto\"><!-- Display settings --><div class=\"mb-6\"><h3 class=\"font-semibold mb-2\">Display</h3><label class=\"block mb-2\">Chrome Behavior <select name=\"chrome_behavior\" class=\"w-full mt-1 px-3 py-2 rounded border\"><option value=\"auto-hide\">Auto Hide</option> <option value=\"always-visible\">Always Visible</option> <option value=\"hide-on-scroll\">Hide on Scroll</option></select></label> <label class=\"block mb-2\">Progress Mode <select name=\"progress_mode\" class=\"w-full mt-1 px-3 py-2 rounded border\"><option value=\"pages\">Pages</option> <option value=\"chapter\">Chapter</option> <option value=\"percentage\">Percentage</option> <option value=\"time-left\">Time Left</option></select></label></div><!-- Reading Theme (reflowable only) --><div class=\"mb-6\" x-show=\"!isFixedLayout\"><h3 class=\"font-semibold mb-2\">Reading Theme</h3><label class=\"block mb-2\"><select name=\"reading_theme\" x-model=\"readingTheme\" @change=\"applyTheme()\" class=\"w-full mt-1 px-3 py-2 rounded border\"><optgroup label=\"📖 Classic Reading\"><option value=\"light\">Light</option> <option value=\"paper\">Paper</option> <option value=\"sepia\">Sepia</option> <option value=\"parchment\">Parchment</option> <option value=\"warm\">Warm</option> <option value=\"candlelight\">Candlelight</option></optgroup> <optgroup label=\"🌤️ Sky & Atmosphere\"><option value=\"azure\">Azure</option> <option value=\"sky\">Sky</option> <option value=\"arctic\">Arctic</option> <option value=\"frost\">Frost</option></optgroup> <optgroup label=\"🌅 Sunset & Warmth\"><option value=\"dusk\">Dusk</option> <option value=\"sunset\">Sunset</option> <option value=\"twilight\">Twilight</option></optgroup> <optgroup label=\"🌲 Nature & Earth\"><option value=\"forest\">Forest</option> <option value=\"moss\">Moss</option> <option value=\"slate\">Slate</option></optgroup> <optgroup label=\"⚡ High Performance\"><option value=\"oled\">OLED</option> <option value=\"solarized\">Solarized</option></optgroup></select></label></div><!-- Typography (reflowable only) --><div class=\"mb-6\" x-show=\"!isFixedLayout\"><h3 class=\"font-semibold mb-2\">Typography</h3><label class=\"block mb-2\">Reading Font <select name=\"reading_font\" x-model=\"readingFont\" @change=\"applyFont()\" class=\"w-full mt-1 px-3 py-2 rounded border\"><option value=\"literata\">Literata (Default)</option> <option value=\"crimson\">Crimson Text</option> <option value=\"source-serif\">Source Serif 4</option> <option value=\"eb-garamond\">EB Garamond</option> <option value=\"libertinus\">Libertinus Serif</option> <option value=\"noto-serif\">Noto Serif</option> <option value=\"charis-sil\">Charis SIL</option> <option value=\"ibm-plex\">IBM Plex Serif</option></select></label> <label class=\"block mb-2\">Font Size <input type=\"range\" name=\"font_size\" x-model.number=\"fontSize\" @change=\"applyFont()\" min=\"12\" max=\"24\" class=\"w-full\"> <span class=\"text-xs\" x-text=\"fontSize + 'px'\" style=\"color: var(--text-secondary)\">16px</span></label> <label class=\"block mb-2\">Line Height <input type=\"range\" name=\"line_height\" x-model.number=\"lineHeight\" @change=\"applyFont()\" min=\"1.0\" max=\"2.5\" step=\"0.1\" class=\"w-full\"> <span class=\"text-xs\" x-text=\"lineHeight\" style=\"color: var(--text-secondary)\">1.6</span></label></div><!-- Navigation --><div class=\"mb-6\" x-show=\"isFixedLayout\"><h3 class=\"font-semibold mb-2\">Navigation</h3><label class=\"flex items-center mb-2\"><input type=\"checkbox\" name=\"double_page_spread\" class=\"mr-2\"> Double Page Spread</label></div><button @click=\"toggleSettings()\" class=\"w-full py-2 bg-blue-600 text-white rounded hover:bg-blue-700\">Done</button></div></div>")
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 13, "<div class=\"dockable-panel\" data-panel=\"settings\" data-side=\"left\" x-ref=\"settingsPanel\"><div class=\"panel-header flex items-center justify-between p-3 cursor-pointer\" @click=\"toggleWindowShade($refs.settingsPanel)\"><h3 class=\"panel-title font-semibold\">⚙️ Settings</h3><div class=\"panel-controls flex items-center gap-2\"><button class=\"window-shade-toggle\">─</button></div></div><div class=\"panel-content p-4 overflow-y-auto\"><!-- Display settings --><div class=\"mb-6\"><h3 class=\"font-semibold mb-2\">Display</h3><label class=\"block mb-2\">Chrome Behavior <select name=\"chrome_behavior\" class=\"w-full mt-1 px-3 py-2 rounded border\"><option value=\"auto-hide\">Auto Hide</option> <option value=\"always-visible\">Always Visible</option> <option value=\"hide-on-scroll\">Hide on Scroll</option></select></label> <label class=\"block mb-2\">Progress Mode <select name=\"progress_mode\" class=\"w-full mt-1 px-3 py-2 rounded border\"><option value=\"pages\">Pages</option> <option value=\"chapter\">Chapter</option> <option value=\"percentage\">Percentage</option> <option value=\"time-left\">Time Left</option></select></label></div><!-- Reading Theme (reflowable only) --><div class=\"mb-6\" x-show=\"!isFixedLayout\"><div class=\"flex items-center justify-between mb-2\"><h3 class=\"font-semibold\">Reading Theme</h3><button @click=\"toggleReadingMode()\" class=\"relative w-12 h-6 rounded-full transition-colors duration-200\" :class=\"readingMode === 'dark' ? 'bg-blue-500' : 'bg-gray-400'\" type=\"button\" :aria-label=\"readingMode === 'dark' ? 'Switch to light mode' : 'Switch to dark mode'\"><span class=\"absolute top-0.5 left-0.5 w-5 h-5 bg-white rounded-full shadow transition-transform duration-200\" :class=\"readingMode === 'dark' ? 'translate-x-6' : 'translate-x-0'\"></span></button></div><label class=\"block mb-2\"><select name=\"reading_theme\" x-model=\"readingTheme\" @change=\"applyTheme()\" class=\"w-full mt-1 px-3 py-2 rounded border\"><optgroup label=\"📖 Classic Reading\"><option value=\"light\">Light</option> <option value=\"paper\">Paper</option> <option value=\"sepia\">Sepia</option> <option value=\"parchment\">Parchment</option> <option value=\"warm\">Warm</option> <option value=\"candlelight\">Candlelight</option></optgroup> <optgroup label=\"🌤️ Sky & Atmosphere\"><option value=\"azure\">Azure</option> <option value=\"sky\">Sky</option> <option value=\"arctic\">Arctic</option> <option value=\"frost\">Frost</option></optgroup> <optgroup label=\"🌅 Sunset & Warmth\"><option value=\"dusk\">Dusk</option> <option value=\"sunset\">Sunset</option> <option value=\"twilight\">Twilight</option></optgroup> <optgroup label=\"🌲 Nature & Earth\"><option value=\"forest\">Forest</option> <option value=\"moss\">Moss</option> <option value=\"slate\">Slate</option></optgroup> <optgroup label=\"⚡ High Performance\"><option value=\"oled\">OLED</option> <option value=\"solarized\">Solarized</option></optgroup></select></label></div><!-- Typography (reflowable only) --><div class=\"mb-6\" x-show=\"!isFixedLayout\"><h3 class=\"font-semibold mb-2\">Typography</h3><label class=\"block mb-2\">Reading Font <select name=\"reading_font\" x-model=\"readingFont\" @change=\"applyFont()\" class=\"w-full mt-1 px-3 py-2 rounded border\"><option value=\"literata\">Literata (Default)</option> <option value=\"crimson\">Crimson Text</option> <option value=\"source-serif\">Source Serif 4</option> <option value=\"eb-garamond\">EB Garamond</option> <option value=\"libertinus\">Libertinus Serif</option> <option value=\"noto-serif\">Noto Serif</option> <option value=\"charis-sil\">Charis SIL</option> <option value=\"ibm-plex\">IBM Plex Serif</option></select></label> <label class=\"block mb-2\">Font Size <input type=\"range\" name=\"font_size\" x-model.number=\"fontSize\" @change=\"applyFont()\" min=\"12\" max=\"24\" class=\"w-full\"> <span class=\"text-xs\" x-text=\"fontSize + 'px'\" style=\"color: var(--text-secondary)\">16px</span></label> <label class=\"block mb-2\">Line Height <input type=\"range\" name=\"line_height\" x-model.number=\"lineHeight\" @change=\"applyFont()\" min=\"1.0\" max=\"2.5\" step=\"0.1\" class=\"w-full\"> <span class=\"text-xs\" x-text=\"lineHeight\" style=\"color: var(--text-secondary)\">1.6</span></label></div><!-- Navigation --><div class=\"mb-6\" x-show=\"isFixedLayout\"><h3 class=\"font-semibold mb-2\">Navigation</h3><label class=\"flex items-center mb-2\"><input type=\"checkbox\" name=\"double_page_spread\" class=\"mr-2\"> Double Page Spread</label></div><button @click=\"toggleSettings()\" class=\"w-full py-2 bg-blue-600 text-white rounded hover:bg-blue-700\">Done</button></div></div>")
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
@@ -293,7 +293,7 @@ func ReaderBookmarksPanel(bookmarks []Bookmark) templ.Component {
 				var templ_7745c5c3_Var11 string
 				templ_7745c5c3_Var11, templ_7745c5c3_Err = templ.JoinStringErrs(bookmark.CfiPosition)
 				if templ_7745c5c3_Err != nil {
-					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/reader.templ`, Line: 334, Col: 38}
+					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/reader.templ`, Line: 348, Col: 38}
 				}
 				_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var11))
 				if templ_7745c5c3_Err != nil {
@@ -306,7 +306,7 @@ func ReaderBookmarksPanel(bookmarks []Bookmark) templ.Component {
 				var templ_7745c5c3_Var12 string
 				templ_7745c5c3_Var12, templ_7745c5c3_Err = templ.JoinStringErrs(bookmark.Title)
 				if templ_7745c5c3_Err != nil {
-					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/reader.templ`, Line: 337, Col: 49}
+					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/reader.templ`, Line: 351, Col: 49}
 				}
 				_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var12))
 				if templ_7745c5c3_Err != nil {
@@ -319,7 +319,7 @@ func ReaderBookmarksPanel(bookmarks []Bookmark) templ.Component {
 				var templ_7745c5c3_Var13 string
 				templ_7745c5c3_Var13, templ_7745c5c3_Err = templ.JoinStringErrs(bookmark.Position)
 				if templ_7745c5c3_Err != nil {
-					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/reader.templ`, Line: 339, Col: 27}
+					return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/reader.templ`, Line: 353, Col: 27}
 				}
 				_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var13))
 				if templ_7745c5c3_Err != nil {

web/src/reader/reader.ts

@@ -84,7 +84,8 @@ document.addEventListener("alpine:init", () => {
     bookmarksOpen: false,
     navigatorOpen: false,
     tocItems: [] as any[],
-    readingTheme: "dark" as string,
+    readingTheme: "light" as string,
+    readingMode: "light" as string,
     readingFont: "literata" as string,
     fontSize: 16 as number,
     lineHeight: 1.6 as number,
@@ -97,13 +98,21 @@ document.addEventListener("alpine:init", () => {
     }) {
       this.settings = await loadSettings();
       if (this.settings) {
-        this.readingTheme = this.settings.reading_theme || "dark";
+        this.readingTheme = this.settings.reading_theme || "light";
         this.readingFont = this.settings.reading_font || "literata";
         this.fontSize = this.settings.font_size || 16;
         this.lineHeight = this.settings.line_height || 1.6;
         if (this.settings.reading_theme) {
           document.body.classList.add(`theme-${this.settings.reading_theme}`);
         }
+        if (this.settings.reading_mode) {
+          this.readingMode = this.settings.reading_mode;
+        } else {
+          this.readingMode = this.detectChromeDarkMode() ? "dark" : "light";
+        }
+        if (this.readingMode === "dark") {
+          document.body.classList.add("dark");
+        }
       }
       this.view = document.getElementById("reader-view") as any;
       const resp = await fetch(config.fileUrl, {
@@ -258,10 +267,29 @@ document.addEventListener("alpine:init", () => {
     applyTheme() {
       document.body.className = document.body.className
         .replace(/theme-(?!tokyo|dracula|nord|solarized|monokai|one-dark|material|catppuccin)[\w-]+/g, "")
+        .replace(/\bdark\b/g, "")
         .trim();
       document.body.classList.add(`theme-${this.readingTheme}`);
+      if (this.readingMode === "dark") {
+        document.body.classList.add("dark");
+      }
       this.applyStyles();
-      saveSettings({ reading_theme: this.readingTheme });
+      saveSettings({
+        reading_theme: this.readingTheme,
+        reading_mode: this.readingMode,
+      });
+    },
+    toggleReadingMode() {
+      this.readingMode = this.readingMode === "dark" ? "light" : "dark";
+      this.applyTheme();
+    },
+    detectChromeDarkMode(): boolean {
+      const darkChromeThemes = [
+        "theme-tokyo-night", "theme-dracula", "theme-nord",
+        "theme-monokai", "theme-one-dark", "theme-material",
+        "theme-catppuccin",
+      ];
+      return darkChromeThemes.some((t) => document.body.classList.contains(t));
     },
     applyFont() {
       this.applyStyles();

web/src/reader/settings-manager.ts

@@ -70,7 +70,8 @@ export function getDefaultSettings(): ReaderSettings {
     chrome_behavior: "auto-hide",
     progress_mode: "pages",
     chrome_theme: "tokyo-night",
-    reading_theme: "dark",
+    reading_theme: "light",
+    reading_mode: "dark",
     reading_font: "literata",
     tap_zone_size: 30,
     auto_scroll: false,