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How do I create a CSS glassmorphism (frosted glass) effect?

The Glassmorphism Generator builds frosted-glass CSS — a semi-transparent tint plus a backdrop-filter that blurs and saturates whatever is behind the element, a thin light border and a soft shadow — with a live preview over local gradient backdrops, an honest text-on-glass contrast read-out, and copy-CSS (including the -webkit- prefix for Safari). It runs 100% in your browser; nothing is uploaded.

What is

Glassmorphism (backdrop-filter)

Glassmorphism is a UI style that mimics frosted glass: an element is given a semi-transparent tinted background and a backdrop-filter (typically blur() with saturate()) that blurs and boosts whatever sits BEHIND it, finished with a thin light 1px border to catch the “edge of glass” and a soft drop shadow for elevation. Unlike filter, backdrop-filter affects the backdrop rather than the element’s own content, so the effect only appears over a colourful or image background. Safari requires the -webkit-backdrop-filter prefix on older versions.

Web Design

Related terms

backdrop-filterblur()saturate()frosted glassrgba tintprefers-reduced-transparency

Frequently Asked Questions

Yes. Your tint colour, blur, saturation and other settings are serialised into CSS entirely on your device — nothing is uploaded, and there is no server or CDN in the processing path.

Everything is 100% client-side. The tool holds the effect as plain numbers and colour strings and serialises the exact CSS declarations — background, backdrop-filter, border, box-shadow — right in your browser tab, including the -webkit-backdrop-filter line Safari needs. The preview backdrops are local CSS gradients, not stock photos, so no external image is fetched. You can copy the full rule, just the declarations, or a single value, and it works offline once the page is cached.

backdrop-filter blurs what is behind the element, so it only shows over a colourful or image background — and it breaks if an ancestor uses overflow:hidden, a transform or a filter.

Two things commonly hide the effect. First, there must be something interesting BEHIND the glass: over a flat page colour there is nothing to blur, so the pane looks flat. Second, a glass element inside an ancestor with overflow:hidden, a transform, a filter, or another backdrop-clipping stacking context can lose or clip the blur — use overflow:clip when you need to clip layout. On older Safari you also need the -webkit-backdrop-filter prefix, which this tool always emits.

It can be. Text on translucent glass shifts with the backdrop and easily fails WCAG contrast; add a tint or solid overlay, keep a 1px border, and honour prefers-reduced-transparency.

The biggest risk is contrast: because the background behind the glass changes pixel-to-pixel, text can drop below the WCAG AA 4.5:1 body-text minimum on busy areas. This tool shows an APPROXIMATE contrast against one representative backdrop colour and warns when it falls below 4.5:1, but you should verify on the real background, raise the tint opacity or add a solid overlay behind the text, keep a subtle 1px border for edge definition, and respect the prefers-reduced-transparency: reduce media query for users who opt out of transparency.

It uses the GPU and can cost frames — large blur radii and stacking many glass panes are heavy on low-end mobiles, and animating it repaints every frame.

backdrop-filter is rendered on the GPU and is more expensive than a plain background. Large blur radii and stacking more than about three glass panes at once can drop frames on low-end phones, and animating the filter itself forces a repaint every frame. Best practice is to keep blur modest, limit the number of glass layers, animate transform/opacity rather than the filter, and add will-change: backdrop-filter only while an element is actually animating. Support is now broad: Chrome/Edge 76+, Firefox 103+, and Safari 9+ (prefixed) or 18+ (unprefixed).

Detailed Explanation

Methodology

How the Glassmorphism Generator Builds the CSS

Glassmorphism (frosted glass) is a semi-transparent tinted background plus a backdrop-filter that blurs — and usually saturates — whatever sits BEHIND the element, finished with a thin light 1px border to catch the “edge of glass” and a soft drop shadow for elevation. This generator’s engine (glassmorphismEngine.ts) holds the effect as typed state and serialises the exact declarations in author order: background: rgba(tint, α); border-radius; -webkit-backdrop-filter and backdrop-filter (blur() + optional saturate()/brightness()); an optional border; and box-shadow with an optional inset top sheen. The -webkit- line is always emitted first so older Safari picks it up.

  • background is an rgba() tint; alpha controls how milky the frost is
  • backdrop-filter = blur(px) with optional saturate(%) and brightness(%)
  • backdrop-filter affects the backdrop, not the element’s own content
  • A thin 1px light border defines the glass edge; box-shadow adds lift
  • -webkit-backdrop-filter is emitted for Safari 9+ compatibility
Use Cases

It Only Works Over a Backdrop — and Clipping Breaks It

Because backdrop-filter blurs what is BEHIND the element, the effect only appears over a colourful or image background; over a flat page colour the pane looks flat. It is also fragile to layout: a glass element inside an ancestor with overflow:hidden, a transform, a filter, or that otherwise establishes a backdrop-clipping stacking context can lose or clip the blur. The fix is to use overflow:clip when you need to clip layout without killing the backdrop, and to keep the glass a direct child of the scene it should frost.

  • No visible effect over a flat background — there is nothing to blur
  • overflow:hidden, transform or filter on an ancestor can clip/break it
  • Use overflow:clip to clip layout without disabling backdrop-filter
  • The tool previews over local CSS-gradient backdrops so the effect shows
Limitations

Contrast Is the #1 Accessibility Risk

Text on translucent glass shifts with the backdrop pixel-to-pixel, so legibility can easily fall below the WCAG AA 4.5:1 body-text minimum over busy areas. This tool reports an APPROXIMATE contrast by alpha-compositing the tint over one representative backdrop colour and warns when it drops below 4.5:1 — but that is guidance, not a guarantee, because the real backdrop varies. Mitigate by raising the tint opacity or adding a solid overlay behind the text, keeping a 1px border for edge definition, and honouring the prefers-reduced-transparency: reduce media query with a solid fallback.

  • WCAG AA body text needs 4.5:1; glass often fails over busy backdrops
  • The read-out approximates contrast against one backdrop colour only
  • Add a tint/solid overlay behind text; keep a 1px border for edges
  • Honour prefers-reduced-transparency: reduce with a solid fallback
Technical Details

Performance: backdrop-filter Costs GPU Frames

backdrop-filter is composited on the GPU and is heavier than a plain background. Large blur radii and stacking more than roughly three glass panes at once can drop frames on low-end mobiles, and ANIMATING backdrop-filter forces a full repaint every frame. Best practice: keep blur modest, limit the number of glass layers, animate transform/opacity rather than the filter itself, and add will-change: backdrop-filter only while an element is actively animating (leaving it on permanently wastes memory). Blur rendering also differs slightly between engines, so verify heavy frost on real devices.

  • Rendered on the GPU — more expensive than a solid background
  • Cap glass panes at ~3 and keep blur radii modest on mobile
  • Animate transform/opacity, not backdrop-filter, to avoid per-frame repaints
  • Use will-change: backdrop-filter only during active animation
Privacy & Security

Private by Design

Everything happens on the user’s device. The tint, blur, saturation, border and shadow values are just numbers and colour strings serialised into CSS locally in the browser tab — there is no server call and no CDN in the processing path. Nothing is uploaded, logged or stored; the preview backdrops are local CSS gradients rather than fetched stock photos, and the output is plain CSS text copied to the clipboard. The tool works offline once loaded.

  • Colours and slider values are serialised into CSS entirely in the browser
  • No upload, no CDN in the processing path, no server, no tracking
  • Preview backdrops are local CSS gradients — no external images
  • Works offline after first load; nothing is stored server-side
backdrop-filter vs filter vs a plain translucent background
ApproachWhat it doesBest for
backdrop-filter: blur()Blurs/saturates the backdrop BEHIND the elementTrue frosted glass over content or imagery
filter: blur()Blurs the element and its OWN contentBlurring an image or the element itself, not the backdrop
background: rgba(...)A flat translucent tint, no blurCheap overlays where no frost is needed
Border + shadow1px light border + soft box-shadowThe “edge of glass” and elevation cues
SupportChrome/Edge 76+, Firefox 103+, Safari 9+ (prefixed)/18+Keep the -webkit- prefix for older Safari

backdrop-filter affects the backdrop; filter affects the element. The effect needs a backdrop to frost and is GPU-expensive at large radii. As of July 2026.