Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/cssom/lib/MediaList.js

@@ -0,0 +1,61 @@
+//.CommonJS
+var CSSOM = {};
+///CommonJS
+
+
+/**
+ * @constructor
+ * @see http://dev.w3.org/csswg/cssom/#the-medialist-interface
+ */
+CSSOM.MediaList = function MediaList(){
+	this.length = 0;
+};
+
+CSSOM.MediaList.prototype = {
+
+	constructor: CSSOM.MediaList,
+
+	/**
+	 * @return {string}
+	 */
+	get mediaText() {
+		return Array.prototype.join.call(this, ", ");
+	},
+
+	/**
+	 * @param {string} value
+	 */
+	set mediaText(value) {
+		var values = value.split(",");
+		var length = this.length = values.length;
+		for (var i=0; i<length; i++) {
+			this[i] = values[i].trim();
+		}
+	},
+
+	/**
+	 * @param {string} medium
+	 */
+	appendMedium: function(medium) {
+		if (Array.prototype.indexOf.call(this, medium) === -1) {
+			this[this.length] = medium;
+			this.length++;
+		}
+	},
+
+	/**
+	 * @param {string} medium
+	 */
+	deleteMedium: function(medium) {
+		var index = Array.prototype.indexOf.call(this, medium);
+		if (index !== -1) {
+			Array.prototype.splice.call(this, index, 1);
+		}
+	}
+
+};
+
+
+//.CommonJS
+exports.MediaList = CSSOM.MediaList;
+///CommonJS