diff --git a/ext/js/pages/settings/popup-preview-controller.js b/ext/js/pages/settings/popup-preview-controller.js
index b2ffbb3a..170d56de 100644
--- a/ext/js/pages/settings/popup-preview-controller.js
+++ b/ext/js/pages/settings/popup-preview-controller.js
@@ -15,17 +15,11 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-/* global
- * wanakana
- */
-
 class PopupPreviewController {
     constructor(settingsController) {
         this._settingsController = settingsController;
-        this._previewVisible = false;
         this._targetOrigin = chrome.runtime.getURL('/').replace(/\/$/, '');
         this._frame = null;
-        this._previewTextInput = null;
         this._customCss = null;
         this._customOuterCss = null;
         this._previewFrameContainer = null;
@@ -41,65 +35,18 @@ class PopupPreviewController {
         this._customCss.addEventListener('settingChanged', this._onCustomCssChange.bind(this), false);
         this._customOuterCss.addEventListener('input', this._onCustomOuterCssChange.bind(this), false);
         this._customOuterCss.addEventListener('settingChanged', this._onCustomOuterCssChange.bind(this), false);
-        this._frame.addEventListener('load', this._onFrameLoad2.bind(this), false);
+        this._frame.addEventListener('load', this._onFrameLoad.bind(this), false);
         this._settingsController.on('optionsContextChanged', this._onOptionsContextChange.bind(this));
     }
 
     // Private
 
-    _onShowPopupPreviewButtonClick() {
-        if (this._previewVisible) { return; }
-        this._showAppearancePreview();
-        this._previewVisible = true;
-    }
-
-    _showAppearancePreview() {
-        const container = document.querySelector('#settings-popup-preview-container');
-        const buttonContainer = document.querySelector('#settings-popup-preview-button-container');
-        const settings = document.querySelector('#settings-popup-preview-settings');
-        const text = document.querySelector('#settings-popup-preview-text');
-        const customCss = document.querySelector('#custom-popup-css');
-        const customOuterCss = document.querySelector('#custom-popup-outer-css');
-        const frame = document.createElement('iframe');
-
-        this._previewTextInput = text;
-        this._frame = frame;
-        this._customCss = customCss;
-        this._customOuterCss = customOuterCss;
-
-        wanakana.bind(text);
-
-        frame.addEventListener('load', this._onFrameLoad.bind(this), false);
-        text.addEventListener('input', this._onTextChange.bind(this), false);
-        customCss.addEventListener('input', this._onCustomCssChange.bind(this), false);
-        customOuterCss.addEventListener('input', this._onCustomOuterCssChange.bind(this), false);
-        this._settingsController.on('optionsContextChanged', this._onOptionsContextChange.bind(this));
-
-        frame.src = '/popup-preview.html';
-        frame.id = 'settings-popup-preview-frame';
-
-        container.appendChild(frame);
-        if (buttonContainer.parentNode !== null) {
-            buttonContainer.parentNode.removeChild(buttonContainer);
-        }
-        settings.style.display = '';
-    }
-
     _onFrameLoad() {
-        this._onOptionsContextChange();
-        this._setText(this._previewTextInput.value);
-    }
-
-    _onFrameLoad2() {
         this._onOptionsContextChange();
         this._onCustomCssChange();
         this._onCustomOuterCssChange();
     }
 
-    _onTextChange(e) {
-        this._setText(e.currentTarget.value);
-    }
-
     _onCustomCssChange() {
         this._invoke('setCustomCss', {css: this._customCss.value});
     }
@@ -113,10 +60,6 @@ class PopupPreviewController {
         this._invoke('updateOptionsContext', {optionsContext});
     }
 
-    _setText(text) {
-        this._invoke('setText', {text});
-    }
-
     _invoke(action, params) {
         if (this._frame === null || this._frame.contentWindow === null) { return; }
         this._frame.contentWindow.postMessage({action, params}, this._targetOrigin);