User interface design principles accessibility

Design user interfaces that are both beautiful and universally accessible. Interface hierarchy: 1. Information architecture: logical content grouping, clear navigation paths. 2. Visual hierarchy: size, color, spacing to guide user attention. 3. Interaction design: intuitive gestures, clear affordances, feedback systems. Accessibility standards (WCAG 2.1 AA): 1. Color contrast: 4.5:1 minimum for normal text, 3:1 for large text. 2. Focus indicators: visible outline for keyboard navigation. 3. Alternative text: descriptive text for images, decorative images marked as such. 4. Semantic markup: proper heading structure, form labels, button descriptions. Design patterns: 1. Touch targets: minimum 44px × 44px for mobile interfaces. 2. Spacing: consistent 8px grid system for visual rhythm. 3. Typography: line height 1.5x font size, maximum 75 characters per line. Tools: Figma with accessibility plugins, Stark for contrast checking, screen readers for testing. User testing: include users with disabilities in design validation, conduct keyboard-only navigation tests.