What cannot be done using Chrome Developer Tools?

Editing and saving the CSS file directly in the Chrome Developer Tools interface allows developers to modify styles and see changes in real time, but these changes are not saved to the original CSS file on the server. The Developer Tools provide a way to temporarily edit CSS for debugging and testing purposes, but once the page is refreshed, any changes made will be lost. Therefore, while you can edit the CSS to see how it affects the page's appearance, you cannot save those changes persistently in the file itself through Developer Tools.

In contrast, the other options describe functionalities that are fully supported by Chrome Developer Tools. You can easily view DOM elements and their associated styles, diagnose JavaScript errors, and inspect network requests made by a webpage, making these capabilities integral to web development and debugging processes.