Creating a complete responsive text editor tool with colorful styling and features in HTML, CSS, and JavaScript is a complex task that would require a substantial amount of code. I can provide you with a simplified example to get you started, but keep in mind that a full-featured text editor is a significant project. Here's a basic example using HTML, CSS, and JavaScript: ```html Text Editor Bold Italic Underline Start typing here... ``` This code provides a simple text editor with a toolbar that allows you to make text bold, italic, and underline. You can extend and customize this code further to add more features and styling as needed. Please note that creating a fully-featured text editor with features like file management, saving, and more advanced styling options would require a much more extensive codebase and potentially the use of external libraries.