Metro UI is a progressive front-end framework for building reactive single-page applications with a Metro-style design language. It provides a component-based UI library with over 150 prebuilt interface elements, a reactive state model that automatically updates the DOM when application data changes, and a responsive grid layout system for mobile-first web development.
The framework uses an HTML-first approach where interactive interfaces are assembled by adding custom HTML attributes to elements, eliminating the need for manual JavaScript glue code. It includes a hash-based SPA router for navigating between views without full page reloads, and a CSS variable theming engine that enables instant switching between dark and light color schemes across all components.
Over 800 vector icons are delivered as a dedicated icon font, allowing scalable, colorable glyphs to be used in buttons, menus, and other interface elements. The responsive grid system adapts page layouts to different screen sizes using media queries and breakpoints, supporting mobile-first responsive design without JavaScript.