Microsoft's cross-platform design system powering Office, Teams, and Windows 11: Segoe UI type, the brand blue #0f6cbd (deepened from the legacy #0078d4), soft 4px-radius controls, layered neutral backgrounds, translucent acrylic and mica materials, and a compact 4px spacing ramp.
Primary actionThe Windows 11 material stack: content sits on subtly layered neutral surfaces (neutralBackground1/2) with 4px-rounded controls, while flyouts and sidebars render in blurred acrylic — depth through translucency rather than heavy shadows.