diff --git a/.gitignore b/.gitignore
index c2658d7..ea0b6b7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
 node_modules/
+yarn.lock
+package-lock.json
diff --git a/lib/ElementQueries.d.ts b/lib/ElementQueries.d.ts
new file mode 100644
index 0000000..00c5d93
--- /dev/null
+++ b/lib/ElementQueries.d.ts
@@ -0,0 +1,14 @@
+export declare class ElementQueries {
+  /**
+   * Attaches to DOMLoadContent
+   */
+  static listen(): void;
+
+  /**
+   * Parses all available CSS and attach ResizeSensor to those elements which have rules attached.
+   * Make sure this is called after 'load' event, because CSS files are not ready when domReady is fired.
+   */
+  static init(): void;
+}
+
+export default ElementQueries;
diff --git a/lib/ElementQueries.js b/lib/ElementQueries.js
new file mode 100644
index 0000000..79ceade
--- /dev/null
+++ b/lib/ElementQueries.js
@@ -0,0 +1,546 @@
+import ResizeSensor from './ResizeSensor.js';
+
+var commonjsGlobal = typeof globalThis !== 'undefined' ? globalThis : typeof window !== 'undefined' ? window : typeof global !== 'undefined' ? global : typeof self !== 'undefined' ? self : {};
+
+function createCommonjsModule(fn, basedir, module) {
+	return module = {
+	  path: basedir,
+	  exports: {},
+	  require: function (path, base) {
+      return commonjsRequire(path, (base === undefined || base === null) ? module.path : base);
+    }
+	}, fn(module, module.exports), module.exports;
+}
+
+function commonjsRequire () {
+	throw new Error('Dynamic requires are not currently supported by @rollup/plugin-commonjs');
+}
+
+var ElementQueries = createCommonjsModule(function (module, exports) {
+
+/**
+ * Copyright Marc J. Schmidt. See the LICENSE file at the top-level
+ * directory of this distribution and at
+ * https://github.com/marcj/css-element-queries/blob/master/LICENSE.
+ */
+(function (root, factory) {
+    {
+        module.exports = factory(ResizeSensor);
+    }
+}(typeof window !== 'undefined' ? window : commonjsGlobal, function (ResizeSensor) {
+
+    /**
+     *
+     * @type {Function}
+     * @constructor
+     */
+    var ElementQueries = function () {
+        //<style> element with our dynamically created styles
+        var cssStyleElement;
+
+        //all rules found for element queries
+        var allQueries = {};
+
+        //association map to identify which selector belongs to a element from the animationstart event.
+        var idToSelectorMapping = [];
+
+        /**
+         *
+         * @param element
+         * @returns {Number}
+         */
+        function getEmSize(element) {
+            if (!element) {
+                element = document.documentElement;
+            }
+            var fontSize = window.getComputedStyle(element, null).fontSize;
+            return parseFloat(fontSize) || 16;
+        }
+
+        /**
+         * Get element size
+         * @param {HTMLElement} element
+         * @returns {Object} {width, height}
+         */
+        function getElementSize(element) {
+            if (!element.getBoundingClientRect) {
+                return {
+                    width: element.offsetWidth,
+                    height: element.offsetHeight
+                }
+            }
+
+            var rect = element.getBoundingClientRect();
+            return {
+                width: Math.round(rect.width),
+                height: Math.round(rect.height)
+            }
+        }
+
+        /**
+         *
+         * @copyright https://github.com/Mr0grog/element-query/blob/master/LICENSE
+         *
+         * @param {HTMLElement} element
+         * @param {*} value
+         * @returns {*}
+         */
+        function convertToPx(element, value) {
+            var numbers = value.split(/\d/);
+            var units = numbers[numbers.length - 1];
+            value = parseFloat(value);
+            switch (units) {
+                case "px":
+                    return value;
+                case "em":
+                    return value * getEmSize(element);
+                case "rem":
+                    return value * getEmSize();
+                // Viewport units!
+                // According to http://quirksmode.org/mobile/tableViewport.html
+                // documentElement.clientWidth/Height gets us the most reliable info
+                case "vw":
+                    return value * document.documentElement.clientWidth / 100;
+                case "vh":
+                    return value * document.documentElement.clientHeight / 100;
+                case "vmin":
+                case "vmax":
+                    var vw = document.documentElement.clientWidth / 100;
+                    var vh = document.documentElement.clientHeight / 100;
+                    var chooser = Math[units === "vmin" ? "min" : "max"];
+                    return value * chooser(vw, vh);
+                default:
+                    return value;
+                // for now, not supporting physical units (since they are just a set number of px)
+                // or ex/ch (getting accurate measurements is hard)
+            }
+        }
+
+        /**
+         *
+         * @param {HTMLElement} element
+         * @param {String} id
+         * @constructor
+         */
+        function SetupInformation(element, id) {
+            this.element = element;
+            var key, option, elementSize, value, actualValue, attrValues, attrValue, attrName;
+
+            var attributes = ['min-width', 'min-height', 'max-width', 'max-height'];
+
+            /**
+             * Extracts the computed width/height and sets to min/max- attribute.
+             */
+            this.call = function () {
+                // extract current dimensions
+                elementSize = getElementSize(this.element);
+
+                attrValues = {};
+
+                for (key in allQueries[id]) {
+                    if (!allQueries[id].hasOwnProperty(key)) {
+                        continue;
+                    }
+                    option = allQueries[id][key];
+
+                    value = convertToPx(this.element, option.value);
+
+                    actualValue = option.property === 'width' ? elementSize.width : elementSize.height;
+                    attrName = option.mode + '-' + option.property;
+                    attrValue = '';
+
+                    if (option.mode === 'min' && actualValue >= value) {
+                        attrValue += option.value;
+                    }
+
+                    if (option.mode === 'max' && actualValue <= value) {
+                        attrValue += option.value;
+                    }
+
+                    if (!attrValues[attrName]) attrValues[attrName] = '';
+                    if (attrValue && -1 === (' ' + attrValues[attrName] + ' ').indexOf(' ' + attrValue + ' ')) {
+                        attrValues[attrName] += ' ' + attrValue;
+                    }
+                }
+
+                for (var k in attributes) {
+                    if (!attributes.hasOwnProperty(k)) continue;
+
+                    if (attrValues[attributes[k]]) {
+                        this.element.setAttribute(attributes[k], attrValues[attributes[k]].substr(1));
+                    } else {
+                        this.element.removeAttribute(attributes[k]);
+                    }
+                }
+            };
+        }
+
+        /**
+         * @param {HTMLElement} element
+         * @param {Object}      id
+         */
+        function setupElement(element, id) {
+            if (!element.elementQueriesSetupInformation) {
+                element.elementQueriesSetupInformation = new SetupInformation(element, id);
+            }
+
+            if (!element.elementQueriesSensor) {
+                element.elementQueriesSensor = new ResizeSensor(element, function () {
+                    element.elementQueriesSetupInformation.call();
+                });
+            }
+        }
+
+        /**
+         * Stores rules to the selector that should be applied once resized.
+         *
+         * @param {String} selector
+         * @param {String} mode min|max
+         * @param {String} property width|height
+         * @param {String} value
+         */
+        function queueQuery(selector, mode, property, value) {
+            if (typeof(allQueries[selector]) === 'undefined') {
+                allQueries[selector] = [];
+                // add animation to trigger animationstart event, so we know exactly when a element appears in the DOM
+
+                var id = idToSelectorMapping.length;
+                cssStyleElement.innerHTML += '\n' + selector + ' {animation: 0.1s element-queries;}';
+                cssStyleElement.innerHTML += '\n' + selector + ' > .resize-sensor {min-width: '+id+'px;}';
+                idToSelectorMapping.push(selector);
+            }
+
+            allQueries[selector].push({
+                mode: mode,
+                property: property,
+                value: value
+            });
+        }
+
+        function getQuery(container) {
+            var query;
+            if (document.querySelectorAll) query = (container) ? container.querySelectorAll.bind(container) : document.querySelectorAll.bind(document);
+            if (!query && 'undefined' !== typeof $$) query = $$;
+            if (!query && 'undefined' !== typeof jQuery) query = jQuery;
+
+            if (!query) {
+                throw 'No document.querySelectorAll, jQuery or Mootools\'s $$ found.';
+            }
+
+            return query;
+        }
+
+        /**
+         * If animationStart didn't catch a new element in the DOM, we can manually search for it
+         */
+        function findElementQueriesElements(container) {
+            var query = getQuery(container);
+
+            for (var selector in allQueries) if (allQueries.hasOwnProperty(selector)) {
+                // find all elements based on the extract query selector from the element query rule
+                var elements = query(selector, container);
+
+                for (var i = 0, j = elements.length; i < j; i++) {
+                    setupElement(elements[i], selector);
+                }
+            }
+        }
+
+        /**
+         *
+         * @param {HTMLElement} element
+         */
+        function attachResponsiveImage(element) {
+            var children = [];
+            var rules = [];
+            var sources = [];
+            var defaultImageId = 0;
+            var lastActiveImage = -1;
+            var loadedImages = [];
+
+            for (var i in element.children) {
+                if (!element.children.hasOwnProperty(i)) continue;
+
+                if (element.children[i].tagName && element.children[i].tagName.toLowerCase() === 'img') {
+                    children.push(element.children[i]);
+
+                    var minWidth = element.children[i].getAttribute('min-width') || element.children[i].getAttribute('data-min-width');
+                    //var minHeight = element.children[i].getAttribute('min-height') || element.children[i].getAttribute('data-min-height');
+                    var src = element.children[i].getAttribute('data-src') || element.children[i].getAttribute('url');
+
+                    sources.push(src);
+
+                    var rule = {
+                        minWidth: minWidth
+                    };
+
+                    rules.push(rule);
+
+                    if (!minWidth) {
+                        defaultImageId = children.length - 1;
+                        element.children[i].style.display = 'block';
+                    } else {
+                        element.children[i].style.display = 'none';
+                    }
+                }
+            }
+
+            lastActiveImage = defaultImageId;
+
+            function check() {
+                var imageToDisplay = false, i;
+
+                for (i in children) {
+                    if (!children.hasOwnProperty(i)) continue;
+
+                    if (rules[i].minWidth) {
+                        if (element.offsetWidth > rules[i].minWidth) {
+                            imageToDisplay = i;
+                        }
+                    }
+                }
+
+                if (!imageToDisplay) {
+                    //no rule matched, show default
+                    imageToDisplay = defaultImageId;
+                }
+
+                if (lastActiveImage !== imageToDisplay) {
+                    //image change
+
+                    if (!loadedImages[imageToDisplay]) {
+                        //image has not been loaded yet, we need to load the image first in memory to prevent flash of
+                        //no content
+
+                        var image = new Image();
+                        image.onload = function () {
+                            children[imageToDisplay].src = sources[imageToDisplay];
+
+                            children[lastActiveImage].style.display = 'none';
+                            children[imageToDisplay].style.display = 'block';
+
+                            loadedImages[imageToDisplay] = true;
+
+                            lastActiveImage = imageToDisplay;
+                        };
+
+                        image.src = sources[imageToDisplay];
+                    } else {
+                        children[lastActiveImage].style.display = 'none';
+                        children[imageToDisplay].style.display = 'block';
+                        lastActiveImage = imageToDisplay;
+                    }
+                } else {
+                    //make sure for initial check call the .src is set correctly
+                    children[imageToDisplay].src = sources[imageToDisplay];
+                }
+            }
+
+            element.resizeSensorInstance = new ResizeSensor(element, check);
+            check();
+        }
+
+        function findResponsiveImages() {
+            var query = getQuery();
+
+            var elements = query('[data-responsive-image],[responsive-image]');
+            for (var i = 0, j = elements.length; i < j; i++) {
+                attachResponsiveImage(elements[i]);
+            }
+        }
+
+        var regex = /,?[\s\t]*([^,\n]*?)((?:\[[\s\t]*?(?:min|max)-(?:width|height)[\s\t]*?[~$\^]?=[\s\t]*?"[^"]*?"[\s\t]*?])+)([^,\n\s\{]*)/mgi;
+        var attrRegex = /\[[\s\t]*?(min|max)-(width|height)[\s\t]*?[~$\^]?=[\s\t]*?"([^"]*?)"[\s\t]*?]/mgi;
+
+        /**
+         * @param {String} css
+         */
+        function extractQuery(css) {
+            var match, smatch, attrs, attrMatch;
+
+            css = css.replace(/'/g, '"');
+            while (null !== (match = regex.exec(css))) {
+                smatch = match[1] + match[3];
+                attrs = match[2];
+
+                while (null !== (attrMatch = attrRegex.exec(attrs))) {
+                    queueQuery(smatch, attrMatch[1], attrMatch[2], attrMatch[3]);
+                }
+            }
+        }
+
+        /**
+         * @param {CssRule[]|String} rules
+         */
+        function readRules(rules) {
+            var selector = '';
+
+            if (!rules) {
+                return;
+            }
+
+            if ('string' === typeof rules) {
+                rules = rules.toLowerCase();
+                if (-1 !== rules.indexOf('min-width') || -1 !== rules.indexOf('max-width')) {
+                    extractQuery(rules);
+                }
+            } else {
+                for (var i = 0, j = rules.length; i < j; i++) {
+                    if (1 === rules[i].type) {
+                        selector = rules[i].selectorText || rules[i].cssText;
+                        if (-1 !== selector.indexOf('min-height') || -1 !== selector.indexOf('max-height')) {
+                            extractQuery(selector);
+                        } else if (-1 !== selector.indexOf('min-width') || -1 !== selector.indexOf('max-width')) {
+                            extractQuery(selector);
+                        }
+                    } else if (4 === rules[i].type) {
+                        readRules(rules[i].cssRules || rules[i].rules);
+                    } else if (3 === rules[i].type) {
+                        if(rules[i].styleSheet.hasOwnProperty("cssRules")) {
+                            readRules(rules[i].styleSheet.cssRules);
+                        }
+                    }
+                }
+            }
+        }
+
+        var defaultCssInjected = false;
+
+        /**
+         * Searches all css rules and setups the event listener to all elements with element query rules..
+         */
+        this.init = function () {
+            var animationStart = 'animationstart';
+            if (typeof document.documentElement.style['webkitAnimationName'] !== 'undefined') {
+                animationStart = 'webkitAnimationStart';
+            } else if (typeof document.documentElement.style['MozAnimationName'] !== 'undefined') {
+                animationStart = 'mozanimationstart';
+            } else if (typeof document.documentElement.style['OAnimationName'] !== 'undefined') {
+                animationStart = 'oanimationstart';
+            }
+
+            document.body.addEventListener(animationStart, function (e) {
+                var element = e.target;
+                var styles = element && window.getComputedStyle(element, null);
+                var animationName = styles && styles.getPropertyValue('animation-name');
+                var requiresSetup = animationName && (-1 !== animationName.indexOf('element-queries'));
+
+                if (requiresSetup) {
+                    element.elementQueriesSensor = new ResizeSensor(element, function () {
+                        if (element.elementQueriesSetupInformation) {
+                            element.elementQueriesSetupInformation.call();
+                        }
+                    });
+
+                    var sensorStyles = window.getComputedStyle(element.resizeSensor, null);
+                    var id = sensorStyles.getPropertyValue('min-width');
+                    id = parseInt(id.replace('px', ''));
+                    setupElement(e.target, idToSelectorMapping[id]);
+                }
+            });
+
+            if (!defaultCssInjected) {
+                cssStyleElement = document.createElement('style');
+                cssStyleElement.type = 'text/css';
+                cssStyleElement.innerHTML = '[responsive-image] > img, [data-responsive-image] {overflow: hidden; padding: 0; } [responsive-image] > img, [data-responsive-image] > img {width: 100%;}';
+
+                //safari wants at least one rule in keyframes to start working
+                cssStyleElement.innerHTML += '\n@keyframes element-queries { 0% { visibility: inherit; } }';
+                document.getElementsByTagName('head')[0].appendChild(cssStyleElement);
+                defaultCssInjected = true;
+            }
+
+            for (var i = 0, j = document.styleSheets.length; i < j; i++) {
+                try {
+                    if (document.styleSheets[i].href && 0 === document.styleSheets[i].href.indexOf('file://')) {
+                        console.warn("CssElementQueries: unable to parse local css files, " + document.styleSheets[i].href);
+                    }
+
+                    readRules(document.styleSheets[i].cssRules || document.styleSheets[i].rules || document.styleSheets[i].cssText);
+                } catch (e) {
+                }
+            }
+
+            findResponsiveImages();
+        };
+
+        /**
+         * Go through all collected rules (readRules()) and attach the resize-listener.
+         * Not necessary to call it manually, since we detect automatically when new elements
+         * are available in the DOM. However, sometimes handy for dirty DOM modifications.
+         *
+         * @param {HTMLElement} container only elements of the container are considered (document.body if not set)
+         */
+        this.findElementQueriesElements = function (container) {
+            findElementQueriesElements(container);
+        };
+
+        this.update = function () {
+            this.init();
+        };
+    };
+
+    ElementQueries.update = function () {
+        ElementQueries.instance.update();
+    };
+
+    /**
+     * Removes all sensor and elementquery information from the element.
+     *
+     * @param {HTMLElement} element
+     */
+    ElementQueries.detach = function (element) {
+        if (element.elementQueriesSetupInformation) {
+            //element queries
+            element.elementQueriesSensor.detach();
+            delete element.elementQueriesSetupInformation;
+            delete element.elementQueriesSensor;
+
+        } else if (element.resizeSensorInstance) {
+            //responsive image
+
+            element.resizeSensorInstance.detach();
+            delete element.resizeSensorInstance;
+        }
+    };
+
+    ElementQueries.init = function () {
+        if (!ElementQueries.instance) {
+            ElementQueries.instance = new ElementQueries();
+        }
+
+        ElementQueries.instance.init();
+    };
+
+    var domLoaded = function (callback) {
+        /* Mozilla, Chrome, Opera */
+        if (document.addEventListener) {
+            document.addEventListener('DOMContentLoaded', callback, false);
+        }
+        /* Safari, iCab, Konqueror */
+        else if (/KHTML|WebKit|iCab/i.test(navigator.userAgent)) {
+            var DOMLoadTimer = setInterval(function () {
+                if (/loaded|complete/i.test(document.readyState)) {
+                    callback();
+                    clearInterval(DOMLoadTimer);
+                }
+            }, 10);
+        }
+        /* Other web browsers */
+        else window.onload = callback;
+    };
+
+    ElementQueries.findElementQueriesElements = function (container) {
+        ElementQueries.instance.findElementQueriesElements(container);
+    };
+
+    ElementQueries.listen = function () {
+        domLoaded(ElementQueries.init);
+    };
+
+    return ElementQueries;
+
+}));
+});
+
+export default ElementQueries;
diff --git a/lib/ResizeSensor.d.ts b/lib/ResizeSensor.d.ts
new file mode 100644
index 0000000..558a053
--- /dev/null
+++ b/lib/ResizeSensor.d.ts
@@ -0,0 +1,36 @@
+export declare interface Size {
+    width: number;
+    height: number;
+}
+
+export declare type ResizeSensorCallback = (size: Size) => void;
+
+export default class ResizeSensor {
+    /**
+     * Creates a new resize sensor on given elements. The provided callback is called max 1 times per requestAnimationFrame and
+     * is called initially.
+     */
+    constructor(element: Element | Element[], callback: ResizeSensorCallback);
+
+    /**
+     * Removes the resize sensor, and stops listening to resize events.
+     */
+    detach(callback?: ResizeSensorCallback): void;
+
+    /**
+     * Resets the resize sensors, so for the next element resize is correctly detected. This is rare cases necessary
+     * when the resize sensor isn't initialised correctly or is in a broken state due to DOM modifications.
+     */
+    reset(): void;
+
+    /**
+     * Removes the resize sensor, and stops listening to resize events.
+     */
+    static detach(element: Element | Element[], callback?: ResizeSensorCallback): void;
+
+    /**
+     * Resets the resize sensors, so for the next element resize is correctly detected. This is rare cases necessary
+     * when the resize sensor isn't initialised correctly or is in a broken state due to DOM modifications.
+     */
+    static reset(element: Element | Element[]): void;
+}
diff --git a/lib/ResizeSensor.js b/lib/ResizeSensor.js
new file mode 100644
index 0000000..f23b992
--- /dev/null
+++ b/lib/ResizeSensor.js
@@ -0,0 +1,388 @@
+var commonjsGlobal = typeof globalThis !== 'undefined' ? globalThis : typeof window !== 'undefined' ? window : typeof global !== 'undefined' ? global : typeof self !== 'undefined' ? self : {};
+
+function createCommonjsModule(fn, basedir, module) {
+	return module = {
+	  path: basedir,
+	  exports: {},
+	  require: function (path, base) {
+      return commonjsRequire(path, (base === undefined || base === null) ? module.path : base);
+    }
+	}, fn(module, module.exports), module.exports;
+}
+
+function commonjsRequire () {
+	throw new Error('Dynamic requires are not currently supported by @rollup/plugin-commonjs');
+}
+
+var ResizeSensor = createCommonjsModule(function (module, exports) {
+
+/**
+ * Copyright Marc J. Schmidt. See the LICENSE file at the top-level
+ * directory of this distribution and at
+ * https://github.com/marcj/css-element-queries/blob/master/LICENSE.
+ */
+(function (root, factory) {
+    {
+        module.exports = factory();
+    }
+}(typeof window !== 'undefined' ? window : commonjsGlobal, function () {
+
+    // Make sure it does not throw in a SSR (Server Side Rendering) situation
+    if (typeof window === "undefined") {
+        return null;
+    }
+    // https://github.com/Semantic-Org/Semantic-UI/issues/3855
+    // https://github.com/marcj/css-element-queries/issues/257
+    var globalWindow = typeof window != 'undefined' && window.Math == Math
+        ? window
+        : typeof self != 'undefined' && self.Math == Math
+            ? self
+            : Function('return this')();
+    // Only used for the dirty checking, so the event callback count is limited to max 1 call per fps per sensor.
+    // In combination with the event based resize sensor this saves cpu time, because the sensor is too fast and
+    // would generate too many unnecessary events.
+    var requestAnimationFrame = globalWindow.requestAnimationFrame ||
+        globalWindow.mozRequestAnimationFrame ||
+        globalWindow.webkitRequestAnimationFrame ||
+        function (fn) {
+            return globalWindow.setTimeout(fn, 20);
+        };
+
+    var cancelAnimationFrame = globalWindow.cancelAnimationFrame ||
+        globalWindow.mozCancelAnimationFrame ||
+        globalWindow.webkitCancelAnimationFrame ||
+        function (timer) {
+            globalWindow.clearTimeout(timer);
+        };
+
+    /**
+     * Iterate over each of the provided element(s).
+     *
+     * @param {HTMLElement|HTMLElement[]} elements
+     * @param {Function}                  callback
+     */
+    function forEachElement(elements, callback){
+        var elementsType = Object.prototype.toString.call(elements);
+        var isCollectionTyped = ('[object Array]' === elementsType
+            || ('[object NodeList]' === elementsType)
+            || ('[object HTMLCollection]' === elementsType)
+            || ('[object Object]' === elementsType)
+            || ('undefined' !== typeof jQuery && elements instanceof jQuery) //jquery
+            || ('undefined' !== typeof Elements && elements instanceof Elements) //mootools
+        );
+        var i = 0, j = elements.length;
+        if (isCollectionTyped) {
+            for (; i < j; i++) {
+                callback(elements[i]);
+            }
+        } else {
+            callback(elements);
+        }
+    }
+
+    /**
+    * Get element size
+    * @param {HTMLElement} element
+    * @returns {Object} {width, height}
+    */
+    function getElementSize(element) {
+        if (!element.getBoundingClientRect) {
+            return {
+                width: element.offsetWidth,
+                height: element.offsetHeight
+            }
+        }
+
+        var rect = element.getBoundingClientRect();
+        return {
+            width: Math.round(rect.width),
+            height: Math.round(rect.height)
+        }
+    }
+
+    /**
+     * Apply CSS styles to element.
+     *
+     * @param {HTMLElement} element
+     * @param {Object} style
+     */
+    function setStyle(element, style) {
+        Object.keys(style).forEach(function(key) {
+            element.style[key] = style[key];
+        });
+    }
+
+    /**
+     * Class for dimension change detection.
+     *
+     * @param {Element|Element[]|Elements|jQuery} element
+     * @param {Function} callback
+     *
+     * @constructor
+     */
+    var ResizeSensor = function(element, callback) {
+        //Is used when checking in reset() only for invisible elements
+        var lastAnimationFrameForInvisibleCheck = 0;
+
+        /**
+         *
+         * @constructor
+         */
+        function EventQueue() {
+            var q = [];
+            this.add = function(ev) {
+                q.push(ev);
+            };
+
+            var i, j;
+            this.call = function(sizeInfo) {
+                for (i = 0, j = q.length; i < j; i++) {
+                    q[i].call(this, sizeInfo);
+                }
+            };
+
+            this.remove = function(ev) {
+                var newQueue = [];
+                for(i = 0, j = q.length; i < j; i++) {
+                    if(q[i] !== ev) newQueue.push(q[i]);
+                }
+                q = newQueue;
+            };
+
+            this.length = function() {
+                return q.length;
+            };
+        }
+
+        /**
+         *
+         * @param {HTMLElement} element
+         * @param {Function}    resized
+         */
+        function attachResizeEvent(element, resized) {
+            if (!element) return;
+            if (element.resizedAttached) {
+                element.resizedAttached.add(resized);
+                return;
+            }
+
+            element.resizedAttached = new EventQueue();
+            element.resizedAttached.add(resized);
+
+            element.resizeSensor = document.createElement('div');
+            element.resizeSensor.dir = 'ltr';
+            element.resizeSensor.className = 'resize-sensor';
+
+            var style = {
+                pointerEvents: 'none',
+                position: 'absolute',
+                left: '0px',
+                top: '0px',
+                right: '0px',
+                bottom: '0px',
+                overflow: 'hidden',
+                zIndex: '-1',
+                visibility: 'hidden',
+                maxWidth: '100%'
+            };
+            var styleChild = {
+                position: 'absolute',
+                left: '0px',
+                top: '0px',
+                transition: '0s',
+            };
+
+            setStyle(element.resizeSensor, style);
+
+            var expand = document.createElement('div');
+            expand.className = 'resize-sensor-expand';
+            setStyle(expand, style);
+
+            var expandChild = document.createElement('div');
+            setStyle(expandChild, styleChild);
+            expand.appendChild(expandChild);
+
+            var shrink = document.createElement('div');
+            shrink.className = 'resize-sensor-shrink';
+            setStyle(shrink, style);
+
+            var shrinkChild = document.createElement('div');
+            setStyle(shrinkChild, styleChild);
+            setStyle(shrinkChild, { width: '200%', height: '200%' });
+            shrink.appendChild(shrinkChild);
+
+            element.resizeSensor.appendChild(expand);
+            element.resizeSensor.appendChild(shrink);
+            element.appendChild(element.resizeSensor);
+
+            var computedStyle = window.getComputedStyle(element);
+            var position = computedStyle ? computedStyle.getPropertyValue('position') : null;
+            if ('absolute' !== position && 'relative' !== position && 'fixed' !== position && 'sticky' !== position) {
+                element.style.position = 'relative';
+            }
+
+            var dirty = false;
+
+            //last request animation frame id used in onscroll event
+            var rafId = 0;
+            var size = getElementSize(element);
+            var lastWidth = 0;
+            var lastHeight = 0;
+            var initialHiddenCheck = true;
+            lastAnimationFrameForInvisibleCheck = 0;
+
+            var resetExpandShrink = function () {
+                var width = element.offsetWidth;
+                var height = element.offsetHeight;
+
+                expandChild.style.width = (width + 10) + 'px';
+                expandChild.style.height = (height + 10) + 'px';
+
+                expand.scrollLeft = width + 10;
+                expand.scrollTop = height + 10;
+
+                shrink.scrollLeft = width + 10;
+                shrink.scrollTop = height + 10;
+            };
+
+            var reset = function() {
+                // Check if element is hidden
+                if (initialHiddenCheck) {
+                    var invisible = element.offsetWidth === 0 && element.offsetHeight === 0;
+                    if (invisible) {
+                        // Check in next frame
+                        if (!lastAnimationFrameForInvisibleCheck){
+                            lastAnimationFrameForInvisibleCheck = requestAnimationFrame(function(){
+                                lastAnimationFrameForInvisibleCheck = 0;
+                                reset();
+                            });
+                        }
+
+                        return;
+                    } else {
+                        // Stop checking
+                        initialHiddenCheck = false;
+                    }
+                }
+
+                resetExpandShrink();
+            };
+            element.resizeSensor.resetSensor = reset;
+
+            var onResized = function() {
+                rafId = 0;
+
+                if (!dirty) return;
+
+                lastWidth = size.width;
+                lastHeight = size.height;
+
+                if (element.resizedAttached) {
+                    element.resizedAttached.call(size);
+                }
+            };
+
+            var onScroll = function() {
+                size = getElementSize(element);
+                dirty = size.width !== lastWidth || size.height !== lastHeight;
+
+                if (dirty && !rafId) {
+                    rafId = requestAnimationFrame(onResized);
+                }
+
+                reset();
+            };
+
+            var addEvent = function(el, name, cb) {
+                if (el.attachEvent) {
+                    el.attachEvent('on' + name, cb);
+                } else {
+                    el.addEventListener(name, cb);
+                }
+            };
+
+            addEvent(expand, 'scroll', onScroll);
+            addEvent(shrink, 'scroll', onScroll);
+
+            // Fix for custom Elements and invisible elements
+            lastAnimationFrameForInvisibleCheck = requestAnimationFrame(function(){
+                lastAnimationFrameForInvisibleCheck = 0;
+                reset();
+            });
+        }
+
+        forEachElement(element, function(elem){
+            attachResizeEvent(elem, callback);
+        });
+
+        this.detach = function(ev) {
+            // clean up the unfinished animation frame to prevent a potential endless requestAnimationFrame of reset
+            if (lastAnimationFrameForInvisibleCheck) {
+                cancelAnimationFrame(lastAnimationFrameForInvisibleCheck);
+                lastAnimationFrameForInvisibleCheck = 0;
+            }
+            ResizeSensor.detach(element, ev);
+        };
+
+        this.reset = function() {
+            //To prevent invoking element.resizeSensor.resetSensor if it's undefined
+            if (element.resizeSensor.resetSensor) {
+                element.resizeSensor.resetSensor();
+            }
+        };
+    };
+
+    ResizeSensor.reset = function(element) {
+        forEachElement(element, function(elem){
+            //To prevent invoking element.resizeSensor.resetSensor if it's undefined
+            if (element.resizeSensor.resetSensor) {
+                elem.resizeSensor.resetSensor();
+            }
+        });
+    };
+
+    ResizeSensor.detach = function(element, ev) {
+        forEachElement(element, function(elem){
+            if (!elem) return;
+            if(elem.resizedAttached && typeof ev === "function"){
+                elem.resizedAttached.remove(ev);
+                if(elem.resizedAttached.length()) return;
+            }
+            if (elem.resizeSensor) {
+                if (elem.contains(elem.resizeSensor)) {
+                    elem.removeChild(elem.resizeSensor);
+                }
+                delete elem.resizeSensor;
+                delete elem.resizedAttached;
+            }
+        });
+    };
+
+    if (typeof MutationObserver !== "undefined") {
+        var observer = new MutationObserver(function (mutations) {
+            for (var i in mutations) {
+                if (mutations.hasOwnProperty(i)) {
+                    var items = mutations[i].addedNodes;
+                    for (var j = 0; j < items.length; j++) {
+                        if (items[j].resizeSensor) {
+                            ResizeSensor.reset(items[j]);
+                        }
+                    }
+                }
+            }
+        });
+
+        document.addEventListener("DOMContentLoaded", function (event) {
+            observer.observe(document.body, {
+                childList: true,
+                subtree: true,
+            });
+        });
+    }
+
+    return ResizeSensor;
+
+}));
+});
+
+export default ResizeSensor;
diff --git a/lib/index.js b/lib/index.js
new file mode 100644
index 0000000..83e01fb
--- /dev/null
+++ b/lib/index.js
@@ -0,0 +1,4 @@
+import ElementQueries from "./ElementQueries.js";
+import ResizeSensor from "./ResizeSensor.js";
+
+export { ElementQueries, ResizeSensor };
diff --git a/package.json b/package.json
index 964230f..2a18773 100644
--- a/package.json
+++ b/package.json
@@ -3,12 +3,11 @@
   "version": "1.2.3",
   "description": "CSS-Element-Queries Polyfill. Proof-of-concept for high-speed element dimension/media queries in valid css.",
   "main": "index.js",
+  "module": "lib/index.js",
   "typings": "css-element-queries.d.ts",
-  "directories": {
-    "test": "test"
-  },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "build": "rollup -c",
+    "prepublishOnly": "npm run build"
   },
   "repository": {
     "type": "git",
@@ -21,7 +20,7 @@
   },
   "homepage": "https://github.com/marcj/css-element-queries",
   "devDependencies": {
-    "grunt": "^0.4.5",
-    "grunt-bump": "^0.3.1"
+    "@rollup/plugin-commonjs": "^14.0.0",
+    "rollup": "^2.22.1"
   }
 }
diff --git a/rollup.config.js b/rollup.config.js
new file mode 100644
index 0000000..7adaa1e
--- /dev/null
+++ b/rollup.config.js
@@ -0,0 +1,30 @@
+import commonjs from "@rollup/plugin-commonjs";
+
+/**
+ * @typedef { import('rollup').RollupOptions } RollupOptions
+ */
+
+/**
+ * @type { RollupOptions[] }
+ */
+const configs = [
+  {
+    input: "src/ElementQueries.js",
+    output: {
+      file: "lib/ElementQueries.js",
+      format: "esm",
+    },
+    external: /ResizeSensor/g,
+    plugins: [commonjs()],
+  },
+  {
+    input: "src/ResizeSensor.js",
+    output: {
+      file: "lib/ResizeSensor.js",
+      format: "esm",
+    },
+    plugins: [commonjs()],
+  },
+];
+
+export default configs;
diff --git a/tests/esm.html b/tests/esm.html
new file mode 100644
index 0000000..b17b87b
--- /dev/null
+++ b/tests/esm.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Css-element-queries ES module Demo</title>
+    <style>
+      #container {
+        background-color: red;
+        height: 20px;
+      }
+    </style>
+  </head>
+  <body>
+    <div id="container"></div>
+    <script type="module">
+      import { ElementQueries, ResizeSensor } from "../lib/index.js";
+      ElementQueries.init();
+      new ResizeSensor(document.getElementById("container"), console.log);
+    </script>
+  </body>
+</html>