CSS Box Shadow Generator

What is a CSS Box Shadow Generator?

A box shadow generator turns the six values behind CSS's box-shadow property — horizontal offset, vertical offset, blur, spread, color, and opacity — into sliders and a live preview, instead of a line of numbers that's hard to picture until it's pasted into a browser. Drag a slider and the preview element updates immediately, so the relationship between "blur" and "spread" or between offset and direction becomes obvious rather than theoretical.

CSS also allows more than one shadow on the same element, comma-separated, which is how most realistic depth effects are built — a soft, spread-out shadow layered under a tighter, darker one reads as more convincing depth than either alone. This tool supports any number of layers, each with its own full set of controls and an inset toggle, and combines them into one ready-to-copy CSS value.

How to use it

How the values work together

The horizontal and vertical offsets move the shadow away from the element — positive values push it right and down, negative values push it left and up. Blur controls how soft the shadow's edge is: zero produces a hard-edged silhouette, while larger values spread the same shadow into a soft gradient. Spread grows or shrinks the shadow's size independently of blur, before the blur softens its edge, which is what lets a shadow look bigger or smaller than the element casting it. Toggling inset flips the shadow to render inside the element's border instead of outside it, which is how pressed-in, carved, or recessed effects are built.

Features & benefits

Why people design shadows visually

A single shadow is easy enough to write from memory, but realistic depth almost always needs more than one layer, and stacking several shadows by hand means re-testing the whole combination every time one value changes. Seeing every layer update together in real time turns that into a much faster loop — nudge a slider, see the full stack respond, and stop the moment it looks right instead of after a dozen save-and-refresh cycles. It's also the fastest way to build a small system of consistent elevation levels — subtle, soft, elevated — that a UI can reuse across cards, buttons, and modals.

Why this runs entirely in your browser

Every layer, slider, and color choice is computed locally in JavaScript — nothing about the shadow being designed is sent to a server. That keeps the preview instant, since there's no round trip for every slider movement, and means the tool keeps working without a network connection once the page has loaded. Nothing persists after the tab is closed.

Getting a shadow that reads well

Low opacity, dark colors tend to look more natural than high-opacity black, since real shadows are rarely fully opaque. A soft, low-opacity, wide-spread layer combined with a tighter, slightly darker layer close to the element usually reads as more convincing depth than one large shadow alone. For inset effects, smaller blur and spread values generally look better than large ones, since an inset shadow is meant to suggest a shallow recess rather than a deep hole.