diff --git a/src/modules/Switcher.js b/src/modules/Switcher.js
index 6659854..b3cfbb5 100644
--- a/src/modules/Switcher.js
+++ b/src/modules/Switcher.js
@@ -65,7 +65,9 @@ var Switcher = class {
 			log_debug('Extension enabled.');
 		}
 		catch(e) {
-			main.notifyError(Me.metadata.name, e.message);
+			if ( e.message ) {
+				main.notifyError(Me.metadata.name, e.message);
+			}
 		}
 	}
 
@@ -84,12 +86,26 @@ var Switcher = class {
 	}
 
 	_on_theme_changed() {
-		this.theme.update_variants();
-		this.theme.set_variant(this.time.current);
+		try {
+			this.theme.update_variants();
+			this.theme.set_variant(this.time.current);
+		}
+		catch(e) {
+			if ( e.message ) {
+				main.notifyError(Me.metadata.name, e.message);
+			}
+		}
 	}
 
 	_on_time_changed() {
-		this.theme.set_variant(this.time.current);
+		try {
+			this.theme.set_variant(this.time.current);
+		}
+		catch(e) {
+			if ( e.message ) {
+				main.notifyError(Me.metadata.name, e.message);
+			}
+		}
 	}
 
 }
diff --git a/src/modules/Themer.js b/src/modules/Themer.js
index 0d3d093..1ac6cf4 100644
--- a/src/modules/Themer.js
+++ b/src/modules/Themer.js
@@ -22,11 +22,15 @@ const { main } = imports.ui;
 
 const Me = extensionUtils.getCurrentExtension();
 const config = Me.imports.config;
+const utils = Me.imports.utils;
 
 const { log_debug } = Me.imports.utils;
 
 const { Variants } = Me.imports.modules.Variants;
 
+const Gettext = imports.gettext.domain(Me.metadata.uuid);
+const _ = Gettext.gettext;
+
 
 /*
 The Themer communicates with the system to get the current theme or set a new
@@ -44,23 +48,44 @@ var Themer = class {
 	}
 
 	enable() {
-		log_debug('Enabling Themer...');
-		this.ready = false;
-		this._listen_to_theme_changes();
-		this.update_variants();
-		this.ready = true;
-		this.emit();
-		log_debug('Themer enabled.');
+		try {
+			log_debug('Enabling Themer...');
+			this.ready = false;
+			this._listen_to_force_manual_status();
+			if ( this._is_force_manual_enabled() ) {
+				log_debug('Using manually set variants.');
+				this._listen_to_prefs_theme_change();
+			}
+			else {
+				log_debug('Automatically detecting variants.');
+				this._listen_to_theme_changes();
+				this.update_variants();
+			}
+			this.ready = true;
+			this.emit();
+			log_debug('Themer enabled.');
+		}
+		catch(e) {
+			if ( e.message ) {
+				main.notifyError(Me.metadata.name, e.message);
+			}
+		}
 	}
 
 	disable() {
 		log_debug('Disabling Themer...');
-		this._stop_listening_to_theme_changes();
-		// GNOME Shell disables extensions when locking the screen. We'll only
-		// reset the theme if the user disables the extension to prevent
-		// flickering when unlocking.
-		if ( !main.screenShield.locked ) {
-			this.reset_theme();
+		this._stop_listening_to_force_manual_status();
+		if ( this._is_force_manual_enabled() ) {
+			this._stop_listening_to_prefs_theme_change();
+		}
+		else {
+			this._stop_listening_to_theme_changes();
+			// GNOME Shell disables extensions when locking the screen. We'll
+			// only reset the theme if the user disables the extension to
+			// prevent flickering when unlocking.
+			if ( !main.screenShield.locked ) {
+				this.reset_theme();
+			}
 		}
 		log_debug('Themer disabled.');
 	}
@@ -99,7 +124,7 @@ var Themer = class {
 	}
 
 	update_variants() {
-		if ( !this._are_variants_up_to_date() ) {
+		if ( !this._are_variants_up_to_date() && !this._is_force_manual_enabled() ) {
 			this._update_variants();
 		}
 	}
@@ -107,8 +132,14 @@ var Themer = class {
 	_update_variants() {
 		if ( this.current_theme ) {
 			const variants = Variants.guess_from(this.current_theme);
-			variants.forEach( (theme, variant) => this.settings.set_string(`theme-${variant}`, theme) );
-			log_debug(`Variants updated: {day: "${variants.get('day')}", night: "${variants.get('night')}"}`);
+			if ( utils.is_theme_installed(variants.get('day')) && utils.is_theme_installed(variants.get('night')) ) {
+				variants.forEach( (theme, variant) => this.settings.set_string(`theme-${variant}`, theme) );
+				log_debug(`Variants updated: {day: "${variants.get('day')}", night: "${variants.get('night')}"}`);
+			}
+			else {
+				const message = _('The extension cannot detect the day and night variants for the "%s" theme. Please choose another theme or manually set variants in the extension preferences.').format(variants.get('original'));
+				throw new Error(message);
+			}
 		}
 	}
 
@@ -116,6 +147,33 @@ var Themer = class {
 		return ( this.current_theme === this.settings.get_string('theme-day') || this.current_theme === this.settings.get_string('theme-night') );
 	}
 
+	_is_force_manual_enabled() {
+		return this.settings.get_boolean('theme-force-manual');
+	}
+
+	_listen_to_force_manual_status() {
+		if ( !this.force_manual_status_connect ) {
+			this.force_manual_status_connect = this.settings.connect(
+				'changed::theme-force-manual',
+				this._on_force_manual_status_changed.bind(this)
+			);
+			log_debug('Listening to manual variants status changes...');
+		}
+	}
+
+	_stop_listening_to_force_manual_status() {
+		if ( this.settings && this.force_manual_status_connect ) {
+			this.settings.disconnect(this.force_manual_status_connect);
+			this.force_manual_status_connect = null;
+			log_debug('Stopped listening to manual variants status changes.');
+		}
+	}
+
+	_on_force_manual_status_changed() {
+		log_debug('Manual variants status has changed.');
+		this.enable();
+	}
+
 	_listen_to_theme_changes() {
 		if ( !this.theme_change_connect ) {
 			this.theme_change_connect = this.theme_gsettings.connect(
@@ -136,7 +194,28 @@ var Themer = class {
 
 	_on_theme_changed() {
 		log_debug(`Theme has changed to "${this.current_theme}".`);
-		this.emit();
+		this.ready ? this.emit() : this.enable();
+	}
+
+	_listen_to_prefs_theme_change() {
+		if ( !this.prefs_theme_change_connect ) {
+			this.prefs_theme_change_connect = new Map();
+			['day', 'night'].forEach(time => {
+				this.prefs_theme_change_connect.set(time, this.settings.connect(
+					`changed::theme-${time}`,
+					this._on_theme_changed.bind(this)
+				));
+				log_debug(`Listening for ${time} theme preference changes...`);
+			});
+		}
+	}
+
+	_stop_listening_to_prefs_theme_change() {
+		if ( this.settings && this.prefs_theme_change_connect ) {
+			this.prefs_theme_change_connect.forEach(connect => this.settings.disconnect(connect));
+			this.prefs_theme_change_connect = null;
+			log_debug('Stopped listening to theme preferences changes.');
+		}
 	}
 
 }
diff --git a/src/modules/Timer.js b/src/modules/Timer.js
index b5ffcd4..bc6c362 100644
--- a/src/modules/Timer.js
+++ b/src/modules/Timer.js
@@ -49,7 +49,7 @@ var Timer = class {
 		this.settings = extensionUtils.getSettings();
 		this.nightlight_gsettings = new Gio.Settings({ schema: config.NIGHTLIGHT_GSETTINGS_SCHEMA });
 		this.location_gsettings = new Gio.Settings({ schema: config.LOCATION_GSETTINGS_SCHEMA });
-		log_debug('Nightlighter initialized.');
+		log_debug('Timer initialized.');
 	}
 
 	enable() {
diff --git a/src/po/fr.po b/src/po/fr.po
index 23d66da..2cd63a4 100644
--- a/src/po/fr.po
+++ b/src/po/fr.po
@@ -7,8 +7,8 @@ msgid ""
 msgstr ""
 "Project-Id-Version: Night Theme Switcher 7\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-06 16:40+0200\n"
-"PO-Revision-Date: 2020-05-06 16:40+0200\n"
+"POT-Creation-Date: 2020-05-09 10:52+0200\n"
+"PO-Revision-Date: 2020-05-09 10:58+0200\n"
 "Last-Translator: Romain Vigier <romain@romainvigier.fr>\n"
 "Language-Team: French - France <romain@romainvigier.fr>\n"
 "Language: fr_FR\n"
@@ -18,7 +18,43 @@ msgstr ""
 "Plural-Forms: nplurals=2; plural=(n > 1)\n"
 "X-Generator: Gtranslator 3.36.0\n"
 
-#: src/prefs.js:58
+#: src/prefs.js:65
+msgid "Theme"
+msgstr "Thème"
+
+#: src/prefs.js:71
+msgid ""
+"The extension will try to automatically detect the day and night variants of "
+"your theme.\n"
+"If the theme you use isn't supported, please <a href=\"https://gitlab.com/"
+"rmnvgr/nightthemeswitcher-gnome-shell-extension/-/issues\">submit a request</"
+"a>.\n"
+"If you prefer, you can manually set variants."
+msgstr ""
+"L’extension essayera de détecter automatiquement les variantes diurne et "
+"nocturne de votre thème.\n"
+"Si le thème que vous utilisez n’est pas supporté, merci <a href=\"https://"
+"gitlab.com/rmnvgr/nightthemeswitcher-gnome-shell-extension/-/issues\">d’en "
+"faire la requête</a>.\n"
+"Si vous préférez, vous pouvez définir manuellement les variantes."
+
+#: src/prefs.js:107
+msgid "Manual variants"
+msgstr "Variantes manuelles"
+
+#: src/prefs.js:151
+msgid "Day variant"
+msgstr "Variante diurne"
+
+#: src/prefs.js:152
+msgid "Night variant"
+msgstr "Variante nocturne"
+
+#: src/prefs.js:197
+msgid "Schedule"
+msgstr "Horaires"
+
+#: src/prefs.js:203
 msgid ""
 "The extension will try to use Night Light or Location Services to "
 "automatically set your current sunrise and sunset times if they are "
@@ -30,49 +66,60 @@ msgstr ""
 "de coucher du soleil.\n"
 "Si vous préférez, vous pouvez définir manuellement un horaire."
 
-#: src/prefs.js:93
-msgid "Manual schedule:"
-msgstr "Horaire manuel :"
+#: src/prefs.js:238
+msgid "Manual schedule"
+msgstr "Horaire manuel"
 
-#: src/prefs.js:138
-msgid "Sunrise: "
-msgstr "Lever du soleil :"
+#: src/prefs.js:283
+msgid "Sunrise"
+msgstr "Lever du soleil"
 
-#: src/prefs.js:139
-msgid "Sunset: "
-msgstr "Coucher du soleil :"
+#: src/prefs.js:284
+msgid "Sunset"
+msgstr "Coucher du soleil"
 
-#: src/modules/Timer.js:268
+#: src/modules/Themer.js:140
+#, javascript-format
+msgid ""
+"The extension cannot detect the day and night variants for the \"%s\" theme. "
+"Please choose another theme or manually set variants in the extension "
+"preferences."
+msgstr ""
+"L’extension ne parvient pas à détecter les variantes diurne et nocturne pour "
+"le thème \"%s\". Merci de sélectionner un autre thème ou de définir "
+"manuellement les variantes dans les préférences de l’extension."
+
+#: src/modules/Timer.js:269
 msgid "Unable to connect to Color DBus proxy."
 msgstr "Impossible de se connecter à la passerelle DBus Color."
 
-#: src/modules/Timer.js:330
+#: src/modules/Timer.js:331
 msgid "Unable to connect to GeoClue Manager DBus proxy."
 msgstr "Impossible de se connecter à la passerelle DBus GeoClue Manager."
 
-#: src/modules/Timer.js:340
+#: src/modules/Timer.js:341
 msgid "Unable to get a GeoClue Client."
 msgstr "Impossible d’obtenir un client GeoClue."
 
-#: src/modules/Timer.js:358
+#: src/modules/Timer.js:359
 msgid "Unable to connect to GeoClue Client DBus proxy."
 msgstr "Impossible de se connecter à la passerelle DBus GeoClue Client."
 
-#: src/modules/Timer.js:417
+#: src/modules/Timer.js:422
 msgid "Unable to connect to GeoClue Location DBus proxy."
 msgstr "Impossible de se connecter à la passerelle DBus GeoClue Location."
 
-#: src/modules/Timer.js:447
+#: src/modules/Timer.js:450
 msgid "Unable to get current location."
 msgstr "Impossible d’obtenir l’emplacement actuel."
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:6
-msgid "Original theme"
-msgstr "Thème original"
+msgid "Use manual variants"
+msgstr "Utiliser des variantes manuelles"
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:7
-msgid "The theme to restore if the extension is disabled"
-msgstr "Thème à restaurer si l’extension est désactivée"
+msgid "Disable automatic variants detection"
+msgstr "Désactive la détection automatique des variantes"
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:11
 msgid "Day theme"
@@ -91,37 +138,54 @@ msgid "The theme to use during nighttime"
 msgstr "Thème à utiliser pendant la nuit"
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:21
+msgid "Original theme"
+msgstr "Thème original"
+
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:22
+msgid "The theme to restore if the extension is disabled"
+msgstr "Thème à restaurer si l’extension est désactivée"
+
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:26
 msgid "Use manual schedule"
 msgstr "Utiliser un horaire manuel"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:22
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:27
 msgid "Disable automatic times detection"
 msgstr "Désactive la détection automatique des horaires"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:31
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:36
 msgid "Time source"
 msgstr "Source des horaires"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:32
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:37
 msgid "The source used to check current time"
 msgstr "Source utilisée pour vérifier les horaires"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:36
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:41
 msgid "Sunrise time"
 msgstr "Heure du lever"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:37
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:42
 msgid "When the day starts"
 msgstr "Quand le jour se lève"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:41
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:46
 msgid "Sunset time"
 msgstr "Heure du coucher"
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:42
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:47
 msgid "When the day ends"
 msgstr "Quand le jour se couche"
 
+#~ msgid "Manual schedule:"
+#~ msgstr "Horaire manuel :"
+
+#~ msgid "Sunrise: "
+#~ msgstr "Lever du soleil :"
+
+#~ msgid "Sunset: "
+#~ msgstr "Coucher du soleil :"
+
 #~ msgid ""
 #~ "Night Light or Location Services must be enabled to use this extension. "
 #~ "Please enable it in your system settings."
diff --git a/src/po/nightthemeswitcher@romainvigier.fr.pot b/src/po/nightthemeswitcher@romainvigier.fr.pot
index 073ddb5..9849bc5 100644
--- a/src/po/nightthemeswitcher@romainvigier.fr.pot
+++ b/src/po/nightthemeswitcher@romainvigier.fr.pot
@@ -6,9 +6,9 @@
 #, fuzzy
 msgid ""
 msgstr ""
-"Project-Id-Version: Night Theme Switcher 25\n"
+"Project-Id-Version: Night Theme Switcher 26\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2020-05-06 16:40+0200\n"
+"POT-Creation-Date: 2020-05-09 10:52+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -17,7 +17,37 @@ msgstr ""
 "Content-Type: text/plain; charset=CHARSET\n"
 "Content-Transfer-Encoding: 8bit\n"
 
-#: src/prefs.js:58
+#: src/prefs.js:65
+msgid "Theme"
+msgstr ""
+
+#: src/prefs.js:71
+msgid ""
+"The extension will try to automatically detect the day and night variants of "
+"your theme.\n"
+"If the theme you use isn't supported, please <a href=\"https://gitlab.com/"
+"rmnvgr/nightthemeswitcher-gnome-shell-extension/-/issues\">submit a request</"
+"a>.\n"
+"If you prefer, you can manually set variants."
+msgstr ""
+
+#: src/prefs.js:107
+msgid "Manual variants"
+msgstr ""
+
+#: src/prefs.js:151
+msgid "Day variant"
+msgstr ""
+
+#: src/prefs.js:152
+msgid "Night variant"
+msgstr ""
+
+#: src/prefs.js:197
+msgid "Schedule"
+msgstr ""
+
+#: src/prefs.js:203
 msgid ""
 "The extension will try to use Night Light or Location Services to "
 "automatically set your current sunrise and sunset times if they are "
@@ -25,48 +55,56 @@ msgid ""
 "If you prefer, you can set a manual schedule."
 msgstr ""
 
-#: src/prefs.js:93
-msgid "Manual schedule:"
+#: src/prefs.js:238
+msgid "Manual schedule"
 msgstr ""
 
-#: src/prefs.js:138
-msgid "Sunrise: "
+#: src/prefs.js:283
+msgid "Sunrise"
 msgstr ""
 
-#: src/prefs.js:139
-msgid "Sunset: "
+#: src/prefs.js:284
+msgid "Sunset"
 msgstr ""
 
-#: src/modules/Timer.js:268
+#: src/modules/Themer.js:140
+#, javascript-format
+msgid ""
+"The extension cannot detect the day and night variants for the \"%s\" theme. "
+"Please choose another theme or manually set variants in the extension "
+"preferences."
+msgstr ""
+
+#: src/modules/Timer.js:269
 msgid "Unable to connect to Color DBus proxy."
 msgstr ""
 
-#: src/modules/Timer.js:330
+#: src/modules/Timer.js:331
 msgid "Unable to connect to GeoClue Manager DBus proxy."
 msgstr ""
 
-#: src/modules/Timer.js:340
+#: src/modules/Timer.js:341
 msgid "Unable to get a GeoClue Client."
 msgstr ""
 
-#: src/modules/Timer.js:358
+#: src/modules/Timer.js:359
 msgid "Unable to connect to GeoClue Client DBus proxy."
 msgstr ""
 
-#: src/modules/Timer.js:417
+#: src/modules/Timer.js:422
 msgid "Unable to connect to GeoClue Location DBus proxy."
 msgstr ""
 
-#: src/modules/Timer.js:447
+#: src/modules/Timer.js:450
 msgid "Unable to get current location."
 msgstr ""
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:6
-msgid "Original theme"
+msgid "Use manual variants"
 msgstr ""
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:7
-msgid "The theme to restore if the extension is disabled"
+msgid "Disable automatic variants detection"
 msgstr ""
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:11
@@ -86,33 +124,41 @@ msgid "The theme to use during nighttime"
 msgstr ""
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:21
-msgid "Use manual schedule"
+msgid "Original theme"
 msgstr ""
 
 #: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:22
+msgid "The theme to restore if the extension is disabled"
+msgstr ""
+
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:26
+msgid "Use manual schedule"
+msgstr ""
+
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:27
 msgid "Disable automatic times detection"
 msgstr ""
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:31
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:36
 msgid "Time source"
 msgstr ""
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:32
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:37
 msgid "The source used to check current time"
 msgstr ""
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:36
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:41
 msgid "Sunrise time"
 msgstr ""
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:37
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:42
 msgid "When the day starts"
 msgstr ""
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:41
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:46
 msgid "Sunset time"
 msgstr ""
 
-#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:42
+#: src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml:47
 msgid "When the day ends"
 msgstr ""
diff --git a/src/prefs.js b/src/prefs.js
index 3018c64..16e70c2 100644
--- a/src/prefs.js
+++ b/src/prefs.js
@@ -23,6 +23,7 @@ const { extensionUtils } = imports.misc;
 
 const Me = extensionUtils.getCurrentExtension();
 const config = Me.imports.config;
+const utils = Me.imports.utils;
 
 const { log_debug } = Me.imports.utils;
 
@@ -41,43 +42,187 @@ function init() {
 }
 
 function buildPrefsWidget() {
-	const prefs_widget = new Gtk.Box({
+	const prefs_widget = new Gtk.Notebook({
+		visible: true
+	});
+
+	/*
+	Theme preferences
+	*/
+
+	const prefs_theme_box = new Gtk.Box({
 		orientation: Gtk.Orientation.VERTICAL,
 		spacing: 30,
 		margin_top: 30,
 		margin_end: 36,
 		margin_start: 36,
+		margin_bottom: 36,
 		valign: Gtk.Align.START,
 		halign: Gtk.Align.CENTER,
-		width_request: 450,
-		margin_bottom: 36,
 		visible: true
-	})
+	});
+	const prefs_theme_box_label = new Gtk.Label({
+		label: _('Theme'),
+		visible: true
+	});
+	prefs_widget.append_page(prefs_theme_box, prefs_theme_box_label);
 
-	const prefs_info = new Gtk.Label({
-		label: _('The extension will try to use Night Light or Location Services to automatically set your current sunrise and sunset times if they are enabled.\nIf you prefer, you can set a manual schedule.'),
-		wrap: true,
+	const prefs_theme_info = new Gtk.Label({
+		label: _('The extension will try to automatically detect the day and night variants of your theme.\nIf the theme you use isn\'t supported, please <a href="https://gitlab.com/rmnvgr/nightthemeswitcher-gnome-shell-extension/-/issues">submit a request</a>.\nIf you prefer, you can manually set variants.'),
+		use_markup: true,
 		max_width_chars: 60,
-		halign: Gtk.Align.FILL,
+		wrap: true,
+		halign: Gtk.Align.START,
 		opacity: 0.7,
 		visible: true
 	});
-	prefs_widget.pack_start(prefs_info, true, true, 0);
+	prefs_theme_box.pack_start(prefs_theme_info, false, false, 0);
 
-	const prefs_frame = new Gtk.Frame({
+	const prefs_theme_frame = new Gtk.Frame({
 		can_focus: false,
 		visible: true
 	});
-	prefs_widget.pack_start(prefs_frame, true, true, 0);
+	prefs_theme_box.pack_start(prefs_theme_frame, false, false, 0);
 
-	const prefs_list = new Gtk.ListBox({
+	const prefs_theme_list = new Gtk.ListBox({
 		border_width: 0,
 		margin: 0,
 		can_focus: false,
 		selection_mode: Gtk.SelectionMode.NONE,
 		visible: true
 	});
-	prefs_frame.add(prefs_list);
+	prefs_theme_frame.add(prefs_theme_list);
+
+	// Force manual toggle
+	const theme_force_manual_box = new Gtk.Box({
+		margin: 16,
+		spacing: 12,
+		orientation: Gtk.Orientation.HORIZONTAL,
+		can_focus: false,
+		visible: true
+	});
+	prefs_theme_list.add(theme_force_manual_box);
+
+	const theme_force_manual_label = new Gtk.Label({
+		label: _('Manual variants'),
+		halign: Gtk.Align.START,
+		visible: true
+	});
+	theme_force_manual_box.pack_start(theme_force_manual_label, true, true, 0);
+
+	const theme_force_manual_toggle = new Gtk.Switch({
+		active: this.settings.get_boolean('time-force-manual'),
+		halign: Gtk.Align.END,
+		visible: true
+	});
+	settings.bind(
+		'theme-force-manual',
+		theme_force_manual_toggle,
+		'active',
+		Gio.SettingsBindFlags.DEFAULT
+	);
+	theme_force_manual_box.pack_start(theme_force_manual_toggle, false, false, 0);
+
+	prefs_theme_list.add(new Gtk.Separator({
+		orientation: Gtk.Orientation.VERTICAL,
+		can_focus: false,
+		visible: true
+	}));
+
+	['day', 'night'].forEach((time, i, times) => {
+		const variant_box = new Gtk.Box({
+			margin: 16,
+			spacing: 12,
+			orientation: Gtk.Orientation.HORIZONTAL,
+			can_focus: false,
+			visible: true
+		});
+		prefs_theme_list.add(variant_box);
+
+		if ( i < times.length - 1 ) {
+			prefs_theme_list.add(new Gtk.Separator({
+				orientation: Gtk.Orientation.VERTICAL,
+				can_focus: false,
+				visible: true
+			}));
+		}
+
+		const variant_labels = new Map([
+			['day', _('Day variant')],
+			['night', _('Night variant')]
+		]);
+		const variant_label = new Gtk.Label({
+			label: variant_labels.get(time),
+			halign: Gtk.Align.START,
+			visible: true
+		})
+		variant_box.pack_start(variant_label, true, true, 0);
+
+		const variant_combo = new Gtk.ComboBoxText({
+			visible: true
+		});
+		const themes = Array.from(utils.get_installed_themes()).sort();
+		themes.forEach(theme => variant_combo.append(theme, theme));
+		settings.bind(
+			`theme-${time}`,
+			variant_combo,
+			'active-id',
+			Gio.SettingsBindFlags.DEFAULT
+		);
+		settings.bind(
+			'theme-force-manual',
+			variant_combo,
+			'sensitive',
+			Gio.SettingsBindFlags.DEFAULT
+		);
+		variant_box.pack_start(variant_combo, false, false, 0);
+
+	});
+
+	/*
+	Schedule preferences
+	*/
+	const prefs_time_box = new Gtk.Box({
+		orientation: Gtk.Orientation.VERTICAL,
+		spacing: 30,
+		margin_top: 30,
+		margin_end: 36,
+		margin_start: 36,
+		margin_bottom: 36,
+		valign: Gtk.Align.START,
+		halign: Gtk.Align.CENTER,
+		visible: true
+	});
+	const prefs_time_box_label = new Gtk.Label({
+		label: _('Schedule'),
+		visible: true
+	});
+	prefs_widget.append_page(prefs_time_box, prefs_time_box_label);
+
+	const prefs_time_info = new Gtk.Label({
+		label: _('The extension will try to use Night Light or Location Services to automatically set your current sunrise and sunset times if they are enabled.\nIf you prefer, you can set a manual schedule.'),
+		max_width_chars: 60,
+		wrap: true,
+		halign: Gtk.Align.START,
+		opacity: 0.7,
+		visible: true
+	});
+	prefs_time_box.pack_start(prefs_time_info, false, false, 0);
+
+	const prefs_time_frame = new Gtk.Frame({
+		can_focus: false,
+		visible: true
+	});
+	prefs_time_box.pack_start(prefs_time_frame, false, false, 0);
+
+	const prefs_time_list = new Gtk.ListBox({
+		border_width: 0,
+		margin: 0,
+		can_focus: false,
+		selection_mode: Gtk.SelectionMode.NONE,
+		visible: true
+	});
+	prefs_time_frame.add(prefs_time_list);
 
 	// Force manual toggle
 	const force_manual_box = new Gtk.Box({
@@ -87,10 +232,10 @@ function buildPrefsWidget() {
 		can_focus: false,
 		visible: true
 	});
-	prefs_list.add(force_manual_box);
+	prefs_time_list.add(force_manual_box);
 
 	const force_manual_label = new Gtk.Label({
-		label: _('Manual schedule:'),
+		label: _('Manual schedule'),
 		halign: Gtk.Align.START,
 		visible: true
 	});
@@ -109,7 +254,7 @@ function buildPrefsWidget() {
 	);
 	force_manual_box.pack_start(force_manual_toggle, false, false, 0);
 
-	prefs_list.add(new Gtk.Separator({
+	prefs_time_list.add(new Gtk.Separator({
 		orientation: Gtk.Orientation.VERTICAL,
 		can_focus: false,
 		visible: true
@@ -124,10 +269,10 @@ function buildPrefsWidget() {
 			can_focus: false,
 			visible: true
 		});
-		prefs_list.add(time_box);
+		prefs_time_list.add(time_box);
 
 		if ( i < suntimes.length - 1 ) {
-			prefs_list.add(new Gtk.Separator({
+			prefs_time_list.add(new Gtk.Separator({
 				orientation: Gtk.Orientation.VERTICAL,
 				can_focus: false,
 				visible: true
@@ -135,8 +280,8 @@ function buildPrefsWidget() {
 		}
 
 		const time_labels = new Map([
-			['sunrise', _('Sunrise: ')],
-			['sunset', _('Sunset: ')]
+			['sunrise', _('Sunrise')],
+			['sunset', _('Sunset')]
 		]);
 		const time_label = new Gtk.Label({
 			label: time_labels.get(suntime),
diff --git a/src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml b/src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml
index 7597ae4..569918e 100644
--- a/src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml
+++ b/src/schemas/org.gnome.shell.extensions.nightthemeswitcher.gschema.xml
@@ -1,21 +1,26 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <schemalist gettext-domain="nightthemeswitcher@romainvigier.fr">
 	<schema id="org.gnome.shell.extensions.nightthemeswitcher" path="/org/gnome/shell/extensions/nightthemeswitcher/">
-		<key name="theme-original" type="s">
-			<default>""</default>
-			<summary>Original theme</summary>
-			<description>The theme to restore if the extension is disabled</description>
+		<key name="theme-force-manual" type="b">
+			<default>false</default>
+			<summary>Use manual variants</summary>
+			<description>Disable automatic variants detection</description>
 		</key>
 		<key name="theme-day" type="s">
-			<default>""</default>
+			<default>"Adwaita"</default>
 			<summary>Day theme</summary>
 			<description>The theme to use during daytime</description>
 		</key>
 		<key name="theme-night" type="s">
-			<default>""</default>
+			<default>"Adwaita-dark"</default>
 			<summary>Night theme</summary>
 			<description>The theme to use during nighttime</description>
 		</key>
+		<key name="theme-original" type="s">
+			<default>""</default>
+			<summary>Original theme</summary>
+			<description>The theme to restore if the extension is disabled</description>
+		</key>
 		<key name="time-force-manual" type="b">
 			<default>false</default>
 			<summary>Use manual schedule</summary>
diff --git a/src/utils.js b/src/utils.js
index eb66e5d..c16b566 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -16,13 +16,60 @@ You should have received a copy of the GNU General Public License along with
 this program. If not, see <http s ://www.gnu.org/licenses/>.
 */
 
+const { Gio, GLib, Gtk } = imports.gi;
 const { extensionUtils } = imports.misc;
 
 const Me = extensionUtils.getCurrentExtension();
 const config = Me.imports.config;
 
+
 var log_debug = function(message) {
 	if ( config.debug ) {
 		log(`[DEBUG] ${Me.metadata.name}: ${message}`);
 	}
 }
+
+var get_installed_themes = function() {
+	const themes = new Set(['Adwaita', 'HighContrast', 'HighContrastInverse']);
+
+	const data_dirs_paths = GLib.get_system_data_dirs().concat(GLib.get_user_data_dir());
+	const themes_dirs_paths = data_dirs_paths.map(path => GLib.build_filenamev([path, 'themes']));
+	themes_dirs_paths.push(GLib.build_filenamev([GLib.get_home_dir(), '.themes']));
+
+	themes_dirs_paths.forEach(themes_dir_path => {
+		const themes_dir = Gio.File.new_for_path(themes_dir_path);
+
+		if ( themes_dir.query_file_type(Gio.FileQueryInfoFlags.NONE, null) !== Gio.FileType.DIRECTORY ) {
+			return;
+		}
+
+		const theme_dirs_enumerator = themes_dir.enumerate_children('', Gio.FileQueryInfoFlags.NONE, null);
+
+		while ( true ) {
+			let theme_dir_info = theme_dirs_enumerator.next_file(null);
+
+			if ( theme_dir_info === null ) {
+				break;
+			}
+
+			const theme_dir = theme_dirs_enumerator.get_child(theme_dir_info);
+
+			[0, Gtk.MINOR_VERSION].forEach(gtk_version => {
+				if ( gtk_version % 2 ) {
+					gtk_version += 1;
+				}
+				const css_file = Gio.File.new_for_path(GLib.build_filenamev([theme_dir.get_path(), `gtk-3.${gtk_version}`, 'gtk.css']));
+				if ( css_file.query_exists(null) ) {
+					themes.add(theme_dir.get_basename());
+				}
+			})
+		}
+		theme_dirs_enumerator.close(null);
+	});
+
+	return themes;
+}
+
+var is_theme_installed = function(theme) {
+	return get_installed_themes().has(theme);
+}