Understanding Box Shadow Parameters
To get the most out of this tool, it helps to visualize how the browser calculates the shadow. The box-shadow property follows this specific order:
Horizontal Offset ($x$): Positive values move the shadow right, negative move it left.
Vertical Offset ($y$): Positive values move the shadow down, negative move it up.
Blur Radius: Determines how "sharp" or "soft" the edge is. A value of $0$ is a hard edge.
Spread Radius: Grows or shrinks the shadow in all directions before the blur is applied.
Color (RGBA): Using RGBA is critical for depth, as solid black shadows often look "muddy."
Advanced Tip: Layering for Realism
Professional UI designers rarely use just one shadow. To create a "natural" lift, they layer multiple shadows: one sharp and dark shadow for the "contact" point, and one large, soft, transparent shadow for the "ambient" light.