A single harsh shadow (e.g., box-shadow: 0 10px 20px rgba(0,0,0,0.4)) looks amateur, heavy, and creates a 'muddy' edge that distracts from content.
To create realistic, smooth shadows that mimic natural ambient lighting, combine two or more subtle shadow declarations:
/* Smooth, realistic card shadow */
box-shadow:
0 1px 2px rgba(0, 0, 0, 0.04), /* Crisp ambient contact shadow */
0 8px 16px rgba(0, 0, 0, 0.06); /* Soft, diffused elevation cast */
Multi-layered shadows maintain crisp edge definition near the element while casting a gentle atmospheric blur into the distance.
Level 3 · Elements of Design II