Angular Cdk

This is your go-to when building custom Angular components that need drag and drop, overlays, virtual scrolling, or accessibility features without the Material Design styling. Version 21 brings signal-based APIs and native popover support for overlays, which is a solid modernization. The examples cover the essentials: setting up overlay positioning for tooltips and dropdowns, handling drag events between lists, virtualizing long lists for performance, and using portals for dynamic content injection. If you're rolling your own component library or need Material-like behavior with custom styling, CDK gives you the primitives without the opinions. The accessibility module alone is worth knowing for focus trapping and screen reader announcements.