diff --git a/README.md b/README.md
index 049f7b010..8d2ff4055 100644
--- a/README.md
+++ b/README.md
@@ -69,6 +69,7 @@ Things might work in Edge 18, Firefox 50-62 and Chrome 54-68 due to one polyfill
 * Replaced momentToNode with proper HTML5 <time>
 * Replaced resize listeners with ResizeObserver
 * Replaced bootstrap.js with native drop-in replacement
+* Replaced dev/Common/ClientStorageDriver/* with Web Storage Objects polyfill
 * Removed pikaday
 * Removed underscore
 * Removed polyfills
@@ -84,23 +85,23 @@ Things might work in Edge 18, Firefox 50-62 and Chrome 54-68 due to one polyfill
 
 |js/*       	|1.14.0 	|native 	|
 |-----------	|--------:	|--------:	|
-|admin.js    	|2.130.942	|  961.538	|
-|app.js      	|4.184.455	|2.624.797	|
-|boot.js     	|  671.522	|   43.742	|
-|libs.js     	|  647.614	|  312.276	|
+|admin.js    	|2.130.942	|  958.580	|
+|app.js      	|4.184.455	|2.591.395	|
+|boot.js     	|  671.522	|   37.334	|
+|libs.js     	|  647.614	|  313.217	|
 |polyfills.js	|  325.834	|        0	|
-|TOTAL      	|7.960.367	|3.942.353	|
+|TOTAL      	|7.960.367	|3.900.526	|
 
 |js/min/*       	|1.14.0   	|native   	|gzip 1.14	|gzip   	|brotli   	|
 |---------------	|--------:	|--------:	|--------:	|--------:	|--------:	|
-|admin.min.js    	|  252.147	|  130.359	| 73.657	| 37.825	| 32.456	|
-|app.min.js      	|  511.202	|  354.068	|140.462	| 93.278	| 74.852	|
-|boot.min.js     	|   66.007	|    5.534	| 22.567	|  2.319	|  1.988	|
-|libs.min.js     	|  572.545	|  295.771	|176.720	| 91.520	| 80.851	|
+|admin.min.js    	|  252.147	|  130.139	| 73.657	| 37.785	| 32.445	|
+|app.min.js      	|  511.202	|  351.142	|140.462	| 92.245	| 74.050	|
+|boot.min.js     	|   66.007	|    4.938	| 22.567	|  2.097	|  1.767	|
+|libs.min.js     	|  572.545	|  296.365	|176.720	| 91.813	| 80.999	|
 |polyfills.min.js	|   32.452	|        0	| 11.312	|      0	|      0	|
-|TOTAL          	|1.434.353	|  785.732	|424.718	|224.942	|190.147	|
+|TOTAL          	|1.434.353	|  782.584	|424.718	|223.940	|189.261	|
 
-648.621 bytes (199.776 gzip) is not much, but it feels faster.
+651.769 bytes (200.778 gzip) is not much, but it feels faster.
 
 ### CSS changes
 
diff --git a/dev/Common/ClientStorageDriver/Cookie.js b/dev/Common/ClientStorageDriver/Cookie.js
deleted file mode 100644
index 17ce9fac0..000000000
--- a/dev/Common/ClientStorageDriver/Cookie.js
+++ /dev/null
@@ -1,162 +0,0 @@
-import { CLIENT_SIDE_STORAGE_INDEX_NAME } from 'Common/Consts';
-
-var Cookies = (() => {
-	function extend (...args) {
-		var result = {};
-		args.forEach(attributes => {
-			for (var key in attributes) {
-				result[key] = attributes[key];
-			}
-		});
-		return result;
-	}
-
-	function decode (s) {
-		return s.replace(/(%[0-9A-Z]{2})+/g, decodeURIComponent);
-	}
-
-	function set (key, value, attributes) {
-		if (typeof document === 'undefined') {
-			return;
-		}
-
-		attributes = extend({
-			path: '/'
-		}, attributes);
-
-		if (typeof attributes.expires === 'number') {
-			attributes.expires = new Date(new Date() * 1 + attributes.expires * 864e+5);
-		}
-
-		// We're using "expires" because "max-age" is not supported by IE
-		attributes.expires = attributes.expires ? attributes.expires.toUTCString() : '';
-
-		try {
-			var result = JSON.stringify(value);
-			if (/^[{[]/.test(result)) {
-				value = result;
-			}
-		} catch (e) {} // eslint-disable-line no-empty
-
-		value = encodeURIComponent(String(value))
-				.replace(/%(23|24|26|2B|3A|3C|3E|3D|2F|3F|40|5B|5D|5E|60|7B|7D|7C)/g, decodeURIComponent);
-
-		key = encodeURIComponent(String(key))
-			.replace(/%(23|24|26|2B|5E|60|7C)/g, decodeURIComponent)
-			.replace(/[()]/g, escape);
-
-		var stringifiedAttributes = '';
-		for (var attributeName in attributes) {
-			if (!attributes[attributeName]) {
-				continue;
-			}
-			stringifiedAttributes += '; ' + attributeName;
-			if (attributes[attributeName] === true) {
-				continue;
-			}
-
-			// Considers RFC 6265 section 5.2:
-			// ...
-			// 3.  If the remaining unparsed-attributes contains a %x3B (";")
-			//     character:
-			// Consume the characters of the unparsed-attributes up to,
-			// not including, the first %x3B (";") character.
-			// ...
-			stringifiedAttributes += '=' + attributes[attributeName].split(';')[0];
-		}
-
-		return (document.cookie = key + '=' + value + stringifiedAttributes);
-	}
-
-	function get (key) {
-		if (typeof document === 'undefined') {
-			return;
-		}
-
-		var jar = {};
-		// To prevent the for loop in the first place assign an empty array
-		// in case there are no cookies at all.
-		var cookies = document.cookie ? document.cookie.split('; ') : [];
-		var i = 0;
-
-		for (; i < cookies.length; i++) {
-			var parts = cookies[i].split('=');
-			var cookie = parts.slice(1).join('=');
-
-			try {
-				var name = decode(parts[0]);
-				cookie = decode(cookie);
-
-				try {
-					cookie = JSON.parse(cookie);
-				} catch (e) {} // eslint-disable-line no-empty
-
-				jar[name] = cookie;
-
-				if (key === name) {
-					break;
-				}
-			} catch (e) {} // eslint-disable-line no-empty
-		}
-
-		return key ? jar[key] : jar;
-	}
-
-	return {
-		set: set,
-		getJSON: key => get(key)
-	};
-})();
-
-
-class CookieDriver {
-	/**
-	 * @param {string} key
-	 * @param {*} data
-	 * @returns {boolean}
-	 */
-	set(key, data) {
-		let result = false,
-			storageResult = null;
-
-		try {
-			storageResult = Cookies.getJSON(CLIENT_SIDE_STORAGE_INDEX_NAME);
-		} catch (e) {} // eslint-disable-line no-empty
-
-		(storageResult || (storageResult = {}))[key] = data;
-
-		try {
-			Cookies.set(CLIENT_SIDE_STORAGE_INDEX_NAME, storageResult, {
-				expires: 30
-			});
-
-			result = true;
-		} catch (e) {} // eslint-disable-line no-empty
-
-		return result;
-	}
-
-	/**
-	 * @param {string} key
-	 * @returns {*}
-	 */
-	get(key) {
-		let result = null;
-
-		try {
-			const storageResult = Cookies.getJSON(CLIENT_SIDE_STORAGE_INDEX_NAME);
-			result = storageResult && null != storageResult[key] ? storageResult[key] : null;
-		} catch (e) {} // eslint-disable-line no-empty
-
-		return result;
-	}
-
-	/**
-	 * @returns {boolean}
-	 */
-	static supported() {
-		return !!(navigator && navigator.cookieEnabled);
-	}
-}
-
-export { CookieDriver, CookieDriver as default };
diff --git a/dev/Common/ClientStorageDriver/LocalStorage.js b/dev/Common/ClientStorageDriver/LocalStorage.js
deleted file mode 100644
index 463634013..000000000
--- a/dev/Common/ClientStorageDriver/LocalStorage.js
+++ /dev/null
@@ -1,64 +0,0 @@
-import { isStorageSupported } from 'Storage/RainLoop';
-import { CLIENT_SIDE_STORAGE_INDEX_NAME } from 'Common/Consts';
-
-class LocalStorageDriver {
-	s = null;
-
-	constructor() {
-		this.s = window.localStorage || null;
-	}
-
-	/**
-	 * @param {string} key
-	 * @param {*} data
-	 * @returns {boolean}
-	 */
-	set(key, data) {
-		if (!this.s) {
-			return false;
-		}
-
-		let storageResult = null;
-		try {
-			const storageValue = this.s.getItem(CLIENT_SIDE_STORAGE_INDEX_NAME) || null;
-			storageResult = null === storageValue ? null : JSON.parse(storageValue);
-		} catch (e) {} // eslint-disable-line no-empty
-
-		(storageResult || (storageResult = {}))[key] = data;
-
-		try {
-			this.s.setItem(CLIENT_SIDE_STORAGE_INDEX_NAME, JSON.stringify(storageResult));
-			return true;
-		} catch (e) {} // eslint-disable-line no-empty
-
-		return false;
-	}
-
-	/**
-	 * @param {string} key
-	 * @returns {*}
-	 */
-	get(key) {
-		if (!this.s) {
-			return null;
-		}
-
-		try {
-			const storageValue = this.s.getItem(CLIENT_SIDE_STORAGE_INDEX_NAME) || null,
-				storageResult = null === storageValue ? null : JSON.parse(storageValue);
-
-			return storageResult && null != storageResult[key] ? storageResult[key] : null;
-		} catch (e) {} // eslint-disable-line no-empty
-
-		return null;
-	}
-
-	/**
-	 * @returns {boolean}
-	 */
-	static supported() {
-		return isStorageSupported('localStorage');
-	}
-}
-
-export { LocalStorageDriver, LocalStorageDriver as default };
diff --git a/dev/Common/HtmlEditor.js b/dev/Common/HtmlEditor.js
index 29d1c4e3c..07737c4ae 100644
--- a/dev/Common/HtmlEditor.js
+++ b/dev/Common/HtmlEditor.js
@@ -90,7 +90,6 @@ class HtmlEditor {
 	onModeChange = null;
 
 	element;
-	$element;
 
 	resize;
 
@@ -113,24 +112,18 @@ class HtmlEditor {
 	}
 
 	runOnBlur() {
-		if (this.onBlur) {
-			this.onBlur();
-		}
+		this.onBlur && this.onBlur();
 	}
 
 	blurTrigger() {
 		if (this.onBlur) {
 			clearTimeout(this.blurTimer);
-			this.blurTimer = setTimeout(() => {
-				this.runOnBlur();
-			}, 200);
+			this.blurTimer = setTimeout(() => this.runOnBlur(), 200);
 		}
 	}
 
 	focusTrigger() {
-		if (this.onBlur) {
-			clearTimeout(this.blurTimer);
-		}
+		this.onBlur && clearTimeout(this.blurTimer);
 	}
 
 	/**
@@ -175,9 +168,7 @@ class HtmlEditor {
 	}
 
 	resetDirty() {
-		if (this.editor) {
-			this.editor.resetDirty();
-		}
+		this.editor && this.editor.resetDirty();
 	}
 
 	/**
@@ -245,9 +236,7 @@ class HtmlEditor {
 				this.editor.setData(html);
 			} catch (e) {} // eslint-disable-line no-empty
 
-			if (focus) {
-				this.focus();
-			}
+			focus && this.focus();
 		}
 	}
 
@@ -272,9 +261,7 @@ class HtmlEditor {
 				} catch (e) {} // eslint-disable-line no-empty
 			}
 
-			if (focus) {
-				this.focus();
-			}
+			focus && this.focus();
 		}
 	}
 
@@ -308,28 +295,16 @@ class HtmlEditor {
 
 				this.editor = window.CKEDITOR.appendTo(this.element, config);
 
-				this.editor.on('key', (event) => {
-					if (event && event.data && EventKeyCode.Tab === event.data.keyCode) {
-						return false;
-					}
+				this.editor.on('key', event => !(event && event.data && EventKeyCode.Tab === event.data.keyCode));
 
-					return true;
-				});
-
-				this.editor.on('blur', () => {
-					this.blurTrigger();
-				});
+				this.editor.on('blur', () => this.blurTrigger());
 
 				this.editor.on('mode', () => {
 					this.blurTrigger();
-					if (this.onModeChange) {
-						this.onModeChange('plain' !== this.editor.mode);
-					}
+					this.onModeChange && this.onModeChange('plain' !== this.editor.mode);
 				});
 
-				this.editor.on('focus', () => {
-					this.focusTrigger();
-				});
+				this.editor.on('focus', () => this.focusTrigger());
 
 				if (window.FileReader) {
 					this.editor.on('drop', (event) => {
@@ -366,9 +341,7 @@ class HtmlEditor {
 
 					this.resize();
 
-					if (this.onReady) {
-						this.onReady();
-					}
+					this.onReady && this.onReady();
 				});
 			};
 
@@ -381,45 +354,35 @@ class HtmlEditor {
 	}
 
 	focus() {
-		if (this.editor) {
-			try {
-				this.editor.focus();
-			} catch (e) {} // eslint-disable-line no-empty
-		}
+		try {
+			this.editor && this.editor.focus();
+		} catch (e) {} // eslint-disable-line no-empty
 	}
 
 	hasFocus() {
-		if (this.editor) {
-			try {
-				return !!this.editor.focusManager.hasFocus;
-			} catch (e) {} // eslint-disable-line no-empty
+		try {
+			return this.editor && !!this.editor.focusManager.hasFocus;
+		} catch (e) {
+			return false;
 		}
-
-		return false;
 	}
 
 	blur() {
-		if (this.editor) {
-			try {
-				this.editor.focusManager.blur(true);
-			} catch (e) {} // eslint-disable-line no-empty
-		}
+		try {
+			this.editor && this.editor.focusManager.blur(true);
+		} catch (e) {} // eslint-disable-line no-empty
 	}
 
 	resizeEditor() {
-		if (this.editor && this.__resizable) {
-			try {
-				this.editor.resize(this.element.clientWidth, this.element.clientHeight);
-			} catch (e) {} // eslint-disable-line no-empty
-		}
+		try {
+			this.editor && this.__resizable && this.editor.resize(this.element.clientWidth, this.element.clientHeight);
+		} catch (e) {} // eslint-disable-line no-empty
 	}
 
 	setReadOnly(value) {
-		if (this.editor) {
-			try {
-				this.editor.setReadOnly(!!value);
-			} catch (e) {} // eslint-disable-line no-empty
-		}
+		try {
+			this.editor && this.editor.setReadOnly(!!value);
+		} catch (e) {} // eslint-disable-line no-empty
 	}
 
 	clear(focus) {
diff --git a/dev/Common/Links.js b/dev/Common/Links.js
index a5afc319f..70f3713c0 100644
--- a/dev/Common/Links.js
+++ b/dev/Common/Links.js
@@ -305,7 +305,7 @@ export function openPgpWorkerPath() {
 export function themePreviewLink(theme) {
 	let prefix = VERSION_PREFIX;
 	if ('@custom' === theme.substr(-7)) {
-		theme = theme.substring(0, theme.length - 7).trim();
+		theme = theme.substr(0, theme.length - 7).trim();
 		prefix = WEB_PREFIX;
 	}
 
diff --git a/dev/Common/Selector.js b/dev/Common/Selector.js
index 58103b1da..0f5ba5fd8 100644
--- a/dev/Common/Selector.js
+++ b/dev/Common/Selector.js
@@ -9,8 +9,6 @@ class Selector {
 	focusedItem;
 	selectedItem;
 
-	itemSelectedThrottle;
-
 	selectedItemUseCallback = true;
 
 	iSelectNextHelper = 0;
@@ -51,7 +49,7 @@ class Selector {
 		this.focusedItem = koFocusedItem || ko.observable(null);
 		this.selectedItem = koSelectedItem || ko.observable(null);
 
-		this.itemSelectedThrottle = (item=>this.itemSelected(item)).debounce(300);
+		const itemSelectedThrottle = (item => this.itemSelected(item)).debounce(300);
 
 		this.listChecked.subscribe((items) => {
 			if (items.length) {
@@ -70,13 +68,11 @@ class Selector {
 		this.selectedItem.subscribe((item) => {
 			if (item) {
 				if (this.isListChecked()) {
-					this.listChecked().forEach(subItem => {
-						subItem.checked(false);
-					});
+					this.listChecked().forEach(subItem => subItem.checked(false));
 				}
 
 				if (this.selectedItemUseCallback) {
-					this.itemSelectedThrottle(item);
+					itemSelectedThrottle(item);
 				}
 			} else if (this.selectedItemUseCallback) {
 				this.itemSelected(null);
@@ -91,11 +87,7 @@ class Selector {
 		this.sItemCheckedSelector = sItemCheckedSelector;
 		this.sItemFocusedSelector = sItemFocusedSelector;
 
-		this.focusedItem.subscribe((item) => {
-			if (item) {
-				this.sLastUid = this.getItemUid(item);
-			}
-		}, this);
+		this.focusedItem.subscribe(item => item && (this.sLastUid = this.getItemUid(item)), this);
 
 		let aCache = [],
 			aCheckedCache = [],
@@ -110,9 +102,7 @@ class Selector {
 							const uid = this.getItemUid(item);
 
 							aCache.push(uid);
-							if (item.checked()) {
-								aCheckedCache.push(uid);
-							}
+							item.checked() && aCheckedCache.push(uid);
 							if (null === mFocused && item.focused()) {
 								mFocused = uid;
 							}
@@ -178,7 +168,8 @@ class Selector {
 							isNextFocused = aCache.find(sUid => {
 								if (getNext && uids.includes(sUid)) {
 									return sUid;
-								} else if (isNextFocused === sUid) {
+								}
+								if (isNextFocused === sUid) {
 									getNext = true;
 								}
 								return false;
@@ -346,13 +337,6 @@ class Selector {
 		return !!(this.oCallbacks.onAutoSelect || (()=>true))();
 	}
 
-	/**
-	 * @param {boolean} up
-	 */
-	doUpUpOrDownDown(up) {
-		(this.oCallbacks.onUpUpOrDownDown || (()=>true))(!!up);
-	}
-
 	/**
 	 * @param {Object} oItem
 	 * @returns {string}
@@ -433,7 +417,7 @@ class Selector {
 					});
 
 					if (!result && (EventKeyCode.Down === iEventKeyCode || EventKeyCode.Up === iEventKeyCode)) {
-						this.doUpUpOrDownDown(EventKeyCode.Up === iEventKeyCode);
+						(this.oCallbacks.onUpUpOrDownDown || (()=>true))(EventKeyCode.Up === iEventKeyCode);
 					}
 				} else if (EventKeyCode.Home === iEventKeyCode || EventKeyCode.End === iEventKeyCode) {
 					if (EventKeyCode.Home === iEventKeyCode) {
diff --git a/dev/Common/Utils.js b/dev/Common/Utils.js
index 6a69e73fe..df28ebd66 100644
--- a/dev/Common/Utils.js
+++ b/dev/Common/Utils.js
@@ -102,7 +102,7 @@ export function splitPlainText(text, len = 100) {
 		newLinePos = 0;
 
 	while (result.length > len) {
-		subText = result.substring(0, len);
+		subText = result.substr(0, len);
 		spacePos = subText.lastIndexOf(' ');
 		newLinePos = subText.lastIndexOf('\n');
 
@@ -114,8 +114,8 @@ export function splitPlainText(text, len = 100) {
 			spacePos = len;
 		}
 
-		prefix += subText.substring(0, spacePos) + '\n';
-		result = result.substring(spacePos + 1);
+		prefix += subText.substr(0, spacePos) + '\n';
+		result = result.substr(spacePos + 1);
 	}
 
 	return prefix + result;
@@ -214,33 +214,14 @@ export function replySubjectAdd(prefix, subject) {
 	return ((prefixIsRe ? 'Re: ' : 'Fwd: ') + (re ? 'Re: ' : '') + (fwd ? 'Fwd: ' : '') + parts.join(':').trim()).trim();
 }
 
-/**
- * @param {number} num
- * @param {number} dec
- * @returns {number}
- */
-export function roundNumber(num, dec) {
-	return Math.round(num * Math.pow(10, dec)) / Math.pow(10, dec);
-}
-
 /**
  * @param {(number|string)} sizeInBytes
  * @returns {string}
  */
 export function friendlySize(sizeInBytes) {
 	sizeInBytes = pInt(sizeInBytes);
-
-	switch (true) {
-		case 1073741824 <= sizeInBytes:
-			return roundNumber(sizeInBytes / 1073741824, 1) + 'GB';
-		case 1048576 <= sizeInBytes:
-			return roundNumber(sizeInBytes / 1048576, 1) + 'MB';
-		case 1024 <= sizeInBytes:
-			return roundNumber(sizeInBytes / 1024, 0) + 'KB';
-		// no default
-	}
-
-	return sizeInBytes + 'B';
+	const sizes = ['B', 'KiB', 'MiB', 'GiB', 'TiB'], i = pInt(Math.floor(Math.log(sizeInBytes) / Math.log(1024)));
+	return (sizeInBytes / Math.pow(1024, i)).toFixed(2>i ? 0 : 1) + sizes[i];
 }
 
 /**
@@ -249,14 +230,14 @@ export function friendlySize(sizeInBytes) {
  */
 export const convertThemeName = theme => {
 	if ('@custom' === theme.substr(-7)) {
-		theme = theme.substring(0, theme.length - 7).trim();
+		theme = theme.substr(0, theme.length - 7).trim();
 	}
 
 	return theme
-			.replace(/[^a-zA-Z0-9]+/g, ' ')
-			.replace(/([A-Z])/g, ' $1')
-			.replace(/\s+/g, ' ')
-			.trim();
+		.replace(/[^a-zA-Z0-9]+/g, ' ')
+		.replace(/([A-Z])/g, ' $1')
+		.replace(/\s+/g, ' ')
+		.trim();
 };
 
 /**
@@ -452,7 +433,7 @@ export function htmlToPlain(html) {
 			iP3 = text.indexOf('__bq__end__', iP1 + 5);
 
 			if ((-1 === iP2 || iP3 < iP2) && iP1 < iP3) {
-				text = text.substring(0, iP1) + convertBlockquote(text.substring(iP1 + 13, iP3)) + text.substring(iP3 + 11);
+				text = text.substr(0, iP1) + convertBlockquote(text.substring(iP1 + 13, iP3)) + text.substr(iP3 + 11);
 				pos = 0;
 			} else if (-1 < iP2 && iP2 < iP3) {
 				pos = iP2 - 1;
@@ -722,7 +703,7 @@ export function changeTheme(value, themeTrigger = ()=>{}) {
 			.replace(/\/Css\/[^/]+\/User\//, '/Css/0/User/')
 			.replace(/\/Hash\/[^/]+\//, '/Hash/-/');
 
-		if ('Json/' !== url.substring(url.length - 5, url.length)) {
+		if ('Json/' !== url.substr(-5)) {
 			url += 'Json/';
 		}
 
diff --git a/dev/Knoin/Knoin.js b/dev/Knoin/Knoin.js
index cfa463e5e..47f119958 100644
--- a/dev/Knoin/Knoin.js
+++ b/dev/Knoin/Knoin.js
@@ -41,14 +41,14 @@ export function hideLoading() {
  */
 export function createCommand(fExecute, fCanExecute = true) {
 	let fResult = null;
-	const fNonEmpty = (...args) => {
-		if (fResult && fResult.canExecute && fResult.canExecute()) {
-			fExecute.apply(null, args);
-		}
-		return false;
-	};
 
-	fResult = fExecute ? fNonEmpty : ()=>{};
+	fResult = fExecute
+		? (...args) => {
+			if (fResult && fResult.canExecute && fResult.canExecute()) {
+				fExecute.apply(null, args);
+			}
+			return false;
+		} : ()=>{};
 	fResult.enabled = ko.observable(true);
 	fResult.isCommand = true;
 
diff --git a/dev/Storage/Client.js b/dev/Storage/Client.js
index 28f212fb6..9d6f433e8 100644
--- a/dev/Storage/Client.js
+++ b/dev/Storage/Client.js
@@ -1,11 +1,6 @@
-import { CookieDriver } from 'Common/ClientStorageDriver/Cookie';
-import { LocalStorageDriver } from 'Common/ClientStorageDriver/LocalStorage';
+import { CLIENT_SIDE_STORAGE_INDEX_NAME } from 'Common/Consts';
 
-const SupportedStorageDriver = [LocalStorageDriver, CookieDriver].find(
-	StorageDriver => StorageDriver && StorageDriver.supported()
-);
-
-const driver = SupportedStorageDriver ? new SupportedStorageDriver() : null;
+const storage = window.localStorage;
 
 /**
  * @param {number} key
@@ -13,7 +8,20 @@ const driver = SupportedStorageDriver ? new SupportedStorageDriver() : null;
  * @returns {boolean}
  */
 export function set(key, data) {
-	return driver ? driver.set('p' + key, data) : false;
+	let storageResult = null;
+	try {
+		const storageValue = storage.getItem(CLIENT_SIDE_STORAGE_INDEX_NAME) || null;
+		storageResult = null === storageValue ? null : JSON.parse(storageValue);
+	} catch (e) {} // eslint-disable-line no-empty
+
+	(storageResult || (storageResult = {}))['p' + key] = data;
+
+	try {
+		storage.setItem(CLIENT_SIDE_STORAGE_INDEX_NAME, JSON.stringify(storageResult));
+		return true;
+	} catch (e) {} // eslint-disable-line no-empty
+
+	return false;
 }
 
 /**
@@ -21,5 +29,13 @@ export function set(key, data) {
  * @returns {*}
  */
 export function get(key) {
-	return driver ? driver.get('p' + key) : null;
+	try {
+		key = 'p' + key;
+		const storageValue = storage.getItem(CLIENT_SIDE_STORAGE_INDEX_NAME) || null,
+			storageResult = null === storageValue ? null : JSON.parse(storageValue);
+
+		return storageResult && null != storageResult[key] ? storageResult[key] : null;
+	} catch (e) {} // eslint-disable-line no-empty
+
+	return null;
 }
diff --git a/dev/Storage/RainLoop.js b/dev/Storage/RainLoop.js
index 98cfb0e8f..fd843b9e2 100644
--- a/dev/Storage/RainLoop.js
+++ b/dev/Storage/RainLoop.js
@@ -1,80 +1,17 @@
 const STORAGE_KEY = '__rlA';
 const TIME_KEY = '__rlT';
 
-/**
- * @param {string} storageName
- * @returns {boolean}
- */
-export function isStorageSupported(storageName) {
-	let storageIsAvailable = false;
-	try {
-		// at: window[storageName] firefox throws SecurityError: The operation is insecure. when in iframe
-		storageIsAvailable = storageName in window && window[storageName] && window[storageName].setItem;
-	} catch (e) {} // eslint-disable-line no-empty
-
-	if (storageIsAvailable) {
-		const s = window[storageName],
-			key = 'testLocalStorage_' + Math.random();
-
-		try {
-			s.setItem(key, key);
-			if (key === s.getItem(key)) {
-				s.removeItem(key);
-				return true;
-			}
-		} catch (e) {} // eslint-disable-line no-empty
-	}
-
-	return false;
-}
-
-const SESS_STORAGE = isStorageSupported('sessionStorage') ? window.sessionStorage || null : null;
-const WIN_STORAGE = window.top || window || null;
-
-const __get = (key) => {
-	let result = null;
-	if (SESS_STORAGE) {
-		result = SESS_STORAGE.getItem(key) || null;
-	} else if (WIN_STORAGE) {
-		const data =
-			WIN_STORAGE.name && '{' === WIN_STORAGE.name.toString()[0]
-				? JSON.parse(WIN_STORAGE.name.toString())
-				: null;
-		result = data ? data[key] || null : null;
-	}
-
-	return result;
-};
-
-const __set = (key, value) => {
-	if (SESS_STORAGE) {
-		SESS_STORAGE.setItem(key, value);
-	} else if (WIN_STORAGE) {
-		let data =
-			WIN_STORAGE.name && '{' === WIN_STORAGE.name.toString()[0]
-				? JSON.parse(WIN_STORAGE.name.toString())
-				: null;
-		data = data || {};
-		data[key] = value;
-
-		WIN_STORAGE.name = JSON.stringify(data);
-	}
-};
+const storage = ()=>window.sessionStorage;
 
 const timestamp = () => Math.round(Date.now() / 1000);
 
-const setTimestamp = () => __set(TIME_KEY, timestamp());
-
-const getTimestamp = () => {
-	const time = __get(TIME_KEY, 0);
-	return time ? parseInt(time, 10) || 0 : 0;
-};
+const setTimestamp = () => storage().setItem(TIME_KEY, timestamp());
 
 /**
  * @returns {string}
  */
 export function getHash() {
-	return __get(STORAGE_KEY);
+	return storage().getItem(STORAGE_KEY) || null;
 }
 
 /**
@@ -84,7 +21,7 @@ export function setHash() {
 	const key = 'AuthAccountHash',
 		appData = window.__rlah_data();
 
-	__set(STORAGE_KEY, appData && appData[key] ? appData[key] : '');
+	storage().setItem(STORAGE_KEY, appData && appData[key] ? appData[key] : '');
 	setTimestamp();
 }
 
@@ -92,7 +29,7 @@ export function setHash() {
  * @returns {void}
  */
 export function clearHash() {
-	__set(STORAGE_KEY, '');
+	storage().setItem(STORAGE_KEY, '');
 	setTimestamp();
 }
 
@@ -100,7 +37,7 @@ export function clearHash() {
  * @returns {boolean}
  */
 export function checkTimestamp() {
-	if (timestamp() > getTimestamp() + 3600000) {
+	if (timestamp() > (parseInt(storage().getItem(TIME_KEY) || 0, 10) || 0) + 3600000) {
 		// 60m
 		clearHash();
 		return true;
diff --git a/dev/View/User/MailBox/MessageList.js b/dev/View/User/MailBox/MessageList.js
index df2050aad..8a3e151e0 100644
--- a/dev/View/User/MailBox/MessageList.js
+++ b/dev/View/User/MailBox/MessageList.js
@@ -104,9 +104,7 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 		this.messageListCompleteLoadingThrottle = MessageStore.messageListCompleteLoadingThrottle;
 		this.messageListCompleteLoadingThrottleForAnimation = MessageStore.messageListCompleteLoadingThrottleForAnimation;
 
-		initOnStartOrLangChange(() => {
-			this.emptySubjectValue = i18n('MESSAGE_LIST/EMPTY_SUBJECT_TEXT');
-		});
+		initOnStartOrLangChange(() => this.emptySubjectValue = i18n('MESSAGE_LIST/EMPTY_SUBJECT_TEXT'));
 
 		this.userQuota = QuotaStore.quota;
 		this.userUsageSize = QuotaStore.usage;
@@ -140,9 +138,7 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 			read: () => 0 < MessageStore.messageListChecked().length,
 			write: (value) => {
 				value = !!value;
-				MessageStore.messageList().forEach(message => {
-					message.checked(value);
-				});
+				MessageStore.messageList().forEach(message => message.checked(value));
 			}
 		});
 
@@ -151,9 +147,7 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 		this.sLastSearchValue = '';
 		this.inputProxyMessageListSearch = ko.computed({
 			read: this.mainMessageListSearch,
-			write: (value) => {
-				this.sLastSearchValue = value;
-			}
+			write: value => this.sLastSearchValue = value
 		});
 
 		this.isIncompleteChecked = ko.computed(() => {
@@ -205,9 +199,7 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 			return this.mobile ? 0 < this.messageListChecked().length : true;
 		});
 
-		this.mobileCheckedStateHide = ko.computed(() => {
-			return this.mobile ? !this.messageListChecked().length : true;
-		});
+		this.mobileCheckedStateHide = ko.computed(() => this.mobile ? !this.messageListChecked().length : true);
 
 		this.messageListFocused = ko.computed(() => Focused.MessageList === AppStore.focusedState());
 
@@ -225,25 +217,17 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 			'.messageListItem.focused'
 		);
 
-		this.selector.on('onItemSelect', (message) => {
-			MessageStore.selectMessage(message);
-		});
+		this.selector.on('onItemSelect', message => MessageStore.selectMessage(message));
 
-		this.selector.on('onItemGetUid', (message) => (message ? message.generateUid() : ''));
+		this.selector.on('onItemGetUid', message => (message ? message.generateUid() : ''));
 
 		this.selector.on('onAutoSelect', () => this.useAutoSelect());
 
-		this.selector.on('onUpUpOrDownDown', (v) => {
-			this.goToUpUpOrDownDown(v);
-		});
+		this.selector.on('onUpUpOrDownDown', v => this.goToUpUpOrDownDown(v));
 
-		addEventListener('mailbox.message-list.selector.go-down', e => {
-			this.selector.goDown(e.detail);
-		});
+		addEventListener('mailbox.message-list.selector.go-down', e => this.selector.goDown(e.detail));
 
-		addEventListener('mailbox.message-list.selector.go-up', e => {
-			this.selector.goUp(e.detail);
-		});
+		addEventListener('mailbox.message-list.selector.go-up', e => this.selector.goUp(e.detail));
 
 		addEventListener('mailbox.message.show', e => {
 			const sFolder = e.detail.Folder, sUid = e.detail.Uid;
@@ -708,16 +692,14 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 	}
 
 	gotoPage(page) {
-		if (page) {
-			setHash(
-				mailBox(
-					FolderStore.currentFolderFullNameHash(),
-					page.value,
-					MessageStore.messageListSearch(),
-					MessageStore.messageListThreadUid()
-				)
-			);
-		}
+		page && setHash(
+			mailBox(
+				FolderStore.currentFolderFullNameHash(),
+				page.value,
+				MessageStore.messageListSearch(),
+				MessageStore.messageListThreadUid()
+			)
+		);
 	}
 
 	gotoThread(message) {
@@ -938,9 +920,7 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 						const next = !!(StorageResultType.Success === result && data && data.Result);
 						setTimeout(() => {
 							this.bPrefetch = false;
-							if (next) {
-								this.prefetchNextTick();
-							}
+							next && this.prefetchNextTick();
 						}, 1000);
 					},
 					message.folderFullNameRaw,
@@ -951,9 +931,8 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 	}
 
 	advancedSearchClick() {
-		if (Settings.capa(Capa.SearchAdv)) {
-			showScreenPopup(require('View/Popup/AdvancedSearch'), [this.mainMessageListSearch()]);
-		}
+		Settings.capa(Capa.SearchAdv)
+			&& showScreenPopup(require('View/Popup/AdvancedSearch'), [this.mainMessageListSearch()]);
 	}
 
 	quotaTooltip() {
@@ -981,25 +960,13 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 			dragAndDropBodyElement: this.dragOverBodyArea()
 		});
 
-		this.dragOver.subscribe((value) => {
-			if (value) {
-				this.selector.scrollToTop();
-			}
-		});
+		this.dragOver.subscribe(value => value && this.selector.scrollToTop());
 
 		oJua
-			.on('onDragEnter', () => {
-				this.dragOverEnter(true);
-			})
-			.on('onDragLeave', () => {
-				this.dragOverEnter(false);
-			})
-			.on('onBodyDragEnter', () => {
-				this.dragOver(true);
-			})
-			.on('onBodyDragLeave', () => {
-				this.dragOver(false);
-			})
+			.on('onDragEnter', () => this.dragOverEnter(true))
+			.on('onDragLeave', () => this.dragOverEnter(false))
+			.on('onBodyDragEnter', () => this.dragOver(true))
+			.on('onBodyDragLeave', () => this.dragOver(false))
 			.on('onSelect', (sUid, oData) => {
 				if (sUid && oData && 'message/rfc822' === oData.Type) {
 					MessageStore.messageListLoading(true);
@@ -1008,9 +975,7 @@ class MessageListMailBoxUserView extends AbstractViewNext {
 
 				return false;
 			})
-			.on('onComplete', () => {
-				getApp().reloadMessageList(true, true);
-			});
+			.on('onComplete', () => getApp().reloadMessageList(true, true));
 
 		return !!oJua;
 	}
diff --git a/dev/View/User/MailBox/MessageView.js b/dev/View/User/MailBox/MessageView.js
index a4e878230..af850d5ec 100644
--- a/dev/View/User/MailBox/MessageView.js
+++ b/dev/View/User/MailBox/MessageView.js
@@ -115,9 +115,7 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 
 		this.showAttachmnetControls = ko.observable(false);
 
-		this.showAttachmnetControlsState = (v) => {
-			Local.set(ClientSideKeyName.MessageAttachmnetControls, !!v);
-		};
+		this.showAttachmnetControlsState = v => Local.set(ClientSideKeyName.MessageAttachmnetControls, !!v);
 
 		this.allowAttachmnetControls = ko.computed(
 			() => this.attachmentsActions().length && Settings.capa(Capa.AttachmentsActions)
@@ -130,33 +128,23 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 		this.downloadAsZipLoading = ko.observable(false);
 		this.downloadAsZipError = ko.observable(false).extend({ falseTimeout: 7000 });
 
-		this.showAttachmnetControls.subscribe((v) => {
-			if (this.message()) {
-				this.message().attachments().forEach(item => {
-					if (item) {
-						item.checked(!!v);
-					}
-				});
-			}
-		});
+		this.showAttachmnetControls.subscribe(v => this.message()
+			&& this.message().attachments().forEach(item => item && item.checked(!!v))
+		);
 
 		this.lastReplyAction_ = ko.observable('');
 		this.lastReplyAction = ko.computed({
 			read: this.lastReplyAction_,
-			write: (value) => {
-				this.lastReplyAction_(
-					[ComposeType.Reply, ComposeType.ReplyAll, ComposeType.Forward].includes(value)
-						? ComposeType.Reply
-						: value
-				);
-			}
+			write: value => this.lastReplyAction_(
+				[ComposeType.Reply, ComposeType.ReplyAll, ComposeType.Forward].includes(value)
+					? ComposeType.Reply
+					: value
+			)
 		});
 
 		this.lastReplyAction(Local.get(ClientSideKeyName.LastReplyAction) || ComposeType.Reply);
 
-		this.lastReplyAction_.subscribe((value) => {
-			Local.set(ClientSideKeyName.LastReplyAction, value);
-		});
+		this.lastReplyAction_.subscribe(value => Local.set(ClientSideKeyName.LastReplyAction, value));
 
 		this.showFullInfo = ko.observable('1' === Local.get(ClientSideKeyName.MessageHeaderFullInfo));
 
@@ -165,16 +153,9 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 
 		this.messageVisibility = ko.computed(() => !this.messageLoadingThrottle() && !!this.message());
 
-		this.message.subscribe((message) => {
-			if (!message) {
-				MessageStore.selectorMessageSelected(null);
-			}
-		});
+		this.message.subscribe(message => (!message) && MessageStore.selectorMessageSelected(null));
 
-		this.canBeRepliedOrForwarded = ko.computed(() => {
-			const v = this.messageVisibility();
-			return !this.isDraftFolder() && v;
-		});
+		this.canBeRepliedOrForwarded = ko.computed(() => !this.isDraftFolder() && this.messageVisibility());
 
 		// commands
 		this.replyCommand = createCommandReplyHelper(ComposeType.Reply);
@@ -242,9 +223,7 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 			return '';
 		});
 
-		this.messageActiveDom.subscribe(dom => {
-			this.bodyBackgroundColor(this.detectDomBackgroundColor(dom));
-		}, this);
+		this.messageActiveDom.subscribe(dom => this.bodyBackgroundColor(this.detectDomBackgroundColor(dom)), this);
 
 		this.message.subscribe((message) => {
 			this.messageActiveDom(null);
@@ -304,16 +283,10 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 
 		this.message.viewTrigger.subscribe(() => {
 			const message = this.message();
-			if (message) {
-				this.viewIsFlagged(message.flagged());
-			} else {
-				this.viewIsFlagged(false);
-			}
+			message ? this.viewIsFlagged(message.flagged()) : this.viewIsFlagged(false);
 		});
 
-		this.fullScreenMode.subscribe((value) => {
-			$htmlCL.toggle('rl-message-fullscreen', value);
-		});
+		this.fullScreenMode.subscribe(value => $htmlCL.toggle('rl-message-fullscreen', value));
 
 		this.messageFocused = ko.computed(() => Focused.MessageView === AppStore.focusedState());
 
@@ -321,9 +294,7 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 			() => MessageStore.messageListCompleteLoadingThrottle() || MessageStore.messageLoadingThrottle()
 		);
 
-		addEventListener('mailbox.message-view.toggle-full-screen', () => {
-			this.toggleFullScreen();
-		});
+		addEventListener('mailbox.message-view.toggle-full-screen', () => this.toggleFullScreen());
 
 		this.attachmentPreview = this.attachmentPreview.bind(this);
 	}
@@ -397,9 +368,7 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 	 * @returns {void}
 	 */
 	replyOrforward(sType) {
-		if (Settings.capa(Capa.Composer)) {
-			showScreenPopup(require('View/Popup/Compose'), [sType, MessageStore.message()]);
-		}
+		Settings.capa(Capa.Composer) && showScreenPopup(require('View/Popup/Compose'), [sType, MessageStore.message()]);
 	}
 
 	checkHeaderHeight() {
@@ -463,9 +432,7 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 					removeInFocus(true);
 				});
 
-				div.on('onCloseAfter.lg', () => {
-					useKeyboardShortcuts(true);
-				});
+				div.on('onCloseAfter.lg', () => useKeyboardShortcuts(true));
 
 				div.lightGallery({
 					dynamic: true,
@@ -487,15 +454,9 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 	}
 
 	onBuild(dom) {
-		this.fullScreenMode.subscribe((value) => {
-			if (value && this.message()) {
-				AppStore.focusedState(Focused.MessageView);
-			}
-		});
+		this.fullScreenMode.subscribe(value => value && this.message() && AppStore.focusedState(Focused.MessageView));
 
-		this.showFullInfo.subscribe((value) => {
-			Local.set(ClientSideKeyName.MessageHeaderFullInfo, value ? '1' : '0');
-		});
+		this.showFullInfo.subscribe(value => Local.set(ClientSideKeyName.MessageHeaderFullInfo, value ? '1' : '0'));
 
 		this.oHeaderDom = dom.querySelector('.messageItemHeader');
 		if (this.oHeaderDom) {
@@ -556,26 +517,22 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 			if (eqs(event, '.messageItemHeader .subjectParent .flagParent')) {
 				// eslint-disable-line prefer-arrow-callback
 				const message = this.message();
-				if (message) {
-					getApp().messageListAction(
-						message.folderFullNameRaw,
-						message.flagged() ? MessageSetAction.UnsetFlag : MessageSetAction.SetFlag,
-						[message]
-					);
-				}
+				message && getApp().messageListAction(
+					message.folderFullNameRaw,
+					message.flagged() ? MessageSetAction.UnsetFlag : MessageSetAction.SetFlag,
+					[message]
+				);
 			}
 
 			el = eqs(event, '.thread-list .flagParent');
 			if (el) {
 				// eslint-disable-line prefer-arrow-callback
 				const message = ko.dataFor(el); // eslint-disable-line no-invalid-this
-				if (message && message.folder && message.uid) {
-					getApp().messageListAction(
-						message.folder,
-						message.flagged() ? MessageSetAction.UnsetFlag : MessageSetAction.SetFlag,
-						[message]
-					);
-				}
+				message && message.folder && message.uid &&  getApp().messageListAction(
+					message.folder,
+					message.flagged() ? MessageSetAction.UnsetFlag : MessageSetAction.SetFlag,
+					[message]
+				);
 
 				this.threadsDropdownTrigger(true);
 
@@ -590,9 +547,7 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 			}
 		});
 
-		keyScopeReal.subscribe((value) => {
-			this.messageDomFocused(KeyState.MessageView === value && !inFocus());
-		});
+		keyScopeReal.subscribe(value => this.messageDomFocused(KeyState.MessageView === value && !inFocus()));
 
 		this.oMessageScrollerDom = dom.querySelector('.messageItem');
 
@@ -604,13 +559,14 @@ class MessageViewMailBoxUserView extends AbstractViewNext {
 	 */
 	escShortcuts() {
 		if (this.viewModelVisibility() && this.message()) {
+			const preview = Layout.NoPreview !== this.layout();
 			if (this.fullScreenMode()) {
 				this.fullScreenMode(false);
 
-				if (Layout.NoPreview !== this.layout()) {
+				if (preview) {
 					AppStore.focusedState(Focused.MessageList);
 				}
-			} else if (Layout.NoPreview === this.layout()) {
+			} else if (!preview) {
 				this.message(null);
 			} else {
 				AppStore.focusedState(Focused.MessageList);
diff --git a/dev/polyfill.js b/dev/polyfill.js
index 3721e96f0..c8bf76e2a 100644
--- a/dev/polyfill.js
+++ b/dev/polyfill.js
@@ -1,3 +1,4 @@
+(w=>{
 
 Array.prototype.flat || Object.defineProperty(Array.prototype, 'flat', {
 	configurable: true,
@@ -15,18 +16,47 @@ Array.prototype.flat || Object.defineProperty(Array.prototype, 'flat', {
 	writable: true
 });
 
-if (!window.ResizeObserver) {
-	window.ResizeObserver = class {
-		constructor(callback) {
-			this.observer = new MutationObserver(callback.debounce(250));
-		}
+w.ResizeObserver || (w.ResizeObserver = class {
+	constructor(callback) {
+		this.observer = new MutationObserver(callback.debounce(250));
+	}
 
-		disconnect() {
-			this.observer.disconnect();
-		}
+	disconnect() {
+		this.observer.disconnect();
+	}
 
-		observe(target) {
-			this.observer.observe(target, { attributes: true, subtree: true, attributeFilter: ['style'] });
-		}
-	};
-}
+	observe(target) {
+		this.observer.observe(target, { attributes: true, subtree: true, attributeFilter: ['style'] });
+	}
+});
+
+const Storage = type => {
+	let name = type+'Storage';
+	try {
+		w[name].setItem('storage', '');
+		w[name].getItem('storage');
+		w[name].removeItem('storage');
+	} catch (e) {
+		console.error(e);
+		const cookieName = encodeURIComponent(name+('session' === type ? w.name || (w.name = Date.now()) : ''));
+
+		// initialise if there's already data
+		let data = document.cookie.match('(^|;) ?'+cookieName+'=([^;]*)(;|$)');
+		data = data ? decodeURIComponent(data[2]) : null;
+		data = data ? JSON.parse(data) : {};
+
+		w[name] = {
+			getItem: key => data[key] === undefined ? null : data[key],
+			setItem: function (key, value) {
+				data[key] = ''+value; // forces the value to a string
+				document.cookie = cookieName+'='+encodeURIComponent(JSON.stringify(data))
+					+"; expires="+('local' === type ? (new Date(Date.now()+(365*24*60*60*1000))).toGMTString() : '')
+					+"; path=/; samesite=strict";
+			}
+		};
+	}
+};
+Storage('local');
+Storage('session');
+
+})(window);