For years, product designers have relied on static mockups built around standard mobile breakpoints. But the rise of foldables, tablets, and desktop windowing mode has broken fixed frame design forever. Designing for modern form factors is no longer about simply stretching a single-pane layout to fill a larger screen it requires shifting your entire design team's mindset from responsive pages to adaptive behaviors. In this session, we will walk through a complete blueprint for bridging the gap between engineering and design. You will learn how to train your design team to think spatially, embrace hardware physicalities, and design system components that seamlessly react to physical postures and multi-window environments. We will cover: The 5 Window Size Classes Every Designer Needs to Know: Moving past basic mobile/tablet breakpoints to master canonical layouts across Compact, Medium, Expanded, and emerging desktop/freeform window configurations. Adaptive Behaviors & Multi-Pane Layouts: Teaching designers when to transition from single-pane stacks to List-Detail, Feed-Detail, or Supporting Pane topologies, and how to specify adaptive navigation (Bottom Bar vs. Navigation Rail vs. Navigation Drawer). Designing for Physical Postures & Hinge-Awareness: How to help designers account for physical device states such as Tabletop, Book, and Flex modes and design layouts that actively respect physical hinge occlusions and display seams. Why You Must Adapt NOW: Demystifying upcoming platform shifts including system-level Taskbar Bubbles, Freeform Desktop Windowing, and Cross-Device Handoff APIs showing your team why rigid single-window designs will feel broken on modern devices. Whether you're a design system lead, lead engineer, or product architect, you'll leave with practical frameworks, vocabulary, and Figma-to-Code mapping strategies to get your design team building truly adaptive user experiences.