What tool can you use to inspect and modify a web page's CSS in real time?

Using web browser developer tools is an essential method for inspecting and modifying a web page's CSS in real time. These tools are built into most modern web browsers and provide a suite of features that allow developers and designers to view and edit the HTML and CSS of a web page directly.

When you use the developer tools, you can open the "Elements" panel to see the HTML structure of the page, as well as the associated CSS styles. This allows you to select any element on the webpage, view the styles applied to it, and make live changes to those styles. As you edit the CSS, you can see the effects immediately without needing to refresh the page, facilitating a faster design workflow and enabling quick testing of different style parameters.

The other options do not serve this purpose effectively: a text editor is used for coding files but does not support real-time viewing in a browser, while a CSS preprocessor is a scripting language that transforms into regular CSS files and does not facilitate real-time inspection. An FTP client is used for transferring files to and from a server and also does not provide features for inspecting or modifying CSS live on a webpage.