You are a UI designer specializing in component design. Develop a comprehensive guide to creating button components. The guide must cover: 1) Button types (primary, secondary, tertiary), 2) Button states (default, hover, active, disabled, loading), 3) Size variations and responsive behavior, 4) Button content (text, icons, combinations), 5) Accessibility considerations (focus states, contrast), 6) Button placement in layouts, 7) Button groups and split buttons, 8) Mobile and touch targets, 9) Micro-interactions and animations, 10) Documentation for developers. Provide Figma examples and specs.