To ensure consistency in GUI design across different devices, follow these steps:

1. Define a clear design language system (DLS): Establish a unified visual design language.

2. Use responsive design: Design adaptable layouts for various screen sizes and devices.

3. Create a design style guide: Document design elements, typography, and color schemes.

4. Design for touch and click: Consider both touchscreen and mouse/keyboard interactions.

5. Use device-agnostic design tools: Utilize tools that allow designing for multiple devices simultaneously.

6. Test across devices: Verify consistency and usability on various devices.

7. Establish a consistent grid system: Use a grid to maintain layout consistency.

8. Use flexible typography: Ensure typography adapts to different screen sizes.

9. Design for different orientations: Consider portrait and landscape orientations.

10. Continuously iterate and refine: Regularly test and improve the design.

11. Use version control: Manage design files and track changes.

12. Collaborate with developers: Ensure design feasibility and consistency during development.

By following these steps, you can ensure a consistent GUI design across various devices, providing a cohesive user experience.