Pesticide for Firefox is a subscription-based web development tool designed to assist developers in identifying and fixing CSS layout issues. This extension visually outlines elements on a webpage, making it easier to spot problematic areas in the layout. With its user-friendly interface, developers can quickly toggle the outlines on and off, providing a straightforward way to diagnose CSS problems without altering the code directly.

The tool is particularly useful for front-end developers who need to ensure their designs are precise and responsive. By highlighting each element, Pesticide allows for a more organized debugging process, ultimately leading to improved website performance and user experience. The extension is a valuable addition to any web developer's toolkit, streamlining the debugging process and enhancing productivity.