Pastels create a sense of calm, friendliness, and lightness. They lower visual tension and make interfaces feel approachable and non-threatening. Different pastel hues carry subtle associations — pale blue suggests trust, soft pink warmth, and mint green freshness.
Low contrast is the primary concern — pastel backgrounds require dark text for legibility, and pastel-on-pastel combinations can fail accessibility standards. Designers need to ensure all text meets WCAG contrast ratios while maintaining the soft overall palette.