CSS Box Shadow & Glow Generator
Visually design CSS box-shadows, soft elevations, and neon glows with instant CSS and Tailwind class output.
How to Use CSS Box Shadow & Glow Generator
- Adjust horizontal (Offset X) and vertical (Offset Y) pixel sliders, including 0px or negative values.
- Configure Blur Radius (0px for hard brutalist shadows up to 100px for soft ambient diffusion) and Spread Radius.
- Enter an RGBA or HEX shadow color and toggle Inset Shadow if you want a recessed neumorphic effect.
- Copy the generated W3C CSS box-shadow rule or the Tailwind CSS arbitrary shadow-[...] utility class.
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Frequently Asked Questions
How does the CSS box-shadow property syntax work?
According to the W3C CSS Backgrounds and Borders Module Level 3 specification, a box-shadow declaration follows the order: optional 'inset' keyword, horizontal offset (offset-x), vertical offset (offset-y), blur radius, spread radius, and color (e.g., box-shadow: 0px 10px 25px -5px rgba(79, 70, 229, 0.4)).
Why does a negative spread radius make a drop shadow look more natural?
A positive spread radius expands the shadow uniformly in all directions, which can look harsh. Using a negative spread radius (such as -5px) paired with a positive vertical offset (such as 10px) pulls the shadow inward from the left and right edges so it appears cast strictly beneath the element.
Can blur radius be zero or negative in CSS box-shadow?
A blur radius of 0px is completely valid and creates a crisp, hard-edged shadow often used in neo-brutalist UI designs. However, negative blur radius values are invalid in CSS and are automatically clamped to 0px by our generator so your stylesheet never breaks.
What is the difference between outer drop shadows and inset shadows?
By default, box-shadow renders an outer drop shadow behind the element frame, making cards and buttons appear elevated above the page. Enabling the 'inset' keyword reverses the shadow inside the element border, creating a recessed, pressed, or sunken appearance ideal for input fields and active button states.
How do I use custom box-shadow values in Tailwind CSS?
Tailwind CSS supports arbitrary box-shadow values using square-bracket notation where spaces are replaced by underscores—for example, shadow-[0px_10px_25px_-5px_rgba(79,70,229,0.4)]. Our generator provides both standard CSS and copy-ready Tailwind utility classes.