ReactOS is a free and open-source operating system that reimplements Windows from the ground up, aiming for binary compatibility with Windows NT applications and drivers. Its desktop can wear several looks — the modern Mizu theme, the flat Lautus and Lunar styles, or the Classic Windows-style Display control panel with its full grid of color schemes. Each style-and-scheme pairing paints the desktop a different background color, on top of the same 48-swatch palette Windows users will recognize.