Finesse is a front-end code editor and inspector for entire websites - new or existing. It has built-in tools that can inspect remote devices, live-reload whenever you save, and supports editing standard html, css, images, etc or works with all preprocessors (Sass, Gulp, React + Webpack, etc). It has an easy-to-use graphical interface for committing directly to git, or you can just share a simple list of your changes with your team.
You could build new iterations of a site that range from quick one-line code changes to sweeping design or technology changes. The tool lets anyone who is either a front-end expert or just starting to learn CSS, HTML and Javascript make their own iterations - no installation required.