SimpleCSS is a visual editor for Cascading Style Sheets (CSS) designed for Mac users. It simplifies the process of creating and modifying style sheets, offering a user-friendly interface. With SimpleCSS, users can easily assign specific values to CSS properties using drop-down menus, color pickers, and checkboxes.

The CSS properties in SimpleCSS are categorized into text, size, frame, and layout sections, making it convenient to navigate and apply styles. Users can preview their changes in real-time at the bottom of the interface, ensuring quick feedback on design adjustments. Additionally, for more advanced users, there is an option to directly edit the CSS source code within the SimpleCSS interface.