🪟 CSS Glassmorphism Generator

Complete Guide: CSS Glassmorphism Generator

Glassmorphism is a UI design style that mimics frosted glass: translucent surfaces with a blur effect that lets background content bleed through, creating depth and a sense of layering. It gained widespread popularity after Apple's macOS Big Sur (2020) and has since become one of the most recognizable modern UI aesthetics.

The Four CSS Properties Behind Glassmorphism

A complete glassmorphism effect requires four properties working together:

.glass-card {
  /* 1. Semi-transparent background */
  background: rgba(255, 255, 255, 0.15);

  /* 2. The blur — this is the defining property */
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px); /* Safari */

  /* 3. Subtle frosted border */
  border: 1px solid rgba(255, 255, 255, 0.25);

  /* 4. Depth shadow */
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);

  /* Supporting properties */
  border-radius: 16px;
}

backdrop-filter: blur() — How It Works

backdrop-filter applies a filter to the area behind an element (everything visible through the element's background). This is fundamentally different from filter: blur(), which blurs the element itself and its children.

The blur radius value determines the frosted glass intensity:

• 4–8px: subtle frosting, background still somewhat readable
• 10–16px: standard glassmorphism look
• 20px+: heavy frost, background almost unrecognizable

The element's background must have some transparency (alpha < 1) for the blur to be visible. A fully opaque background blocks the backdrop effect entirely.

Browser Support and the Safari Prefix

backdrop-filter is supported in Chrome 76+, Edge 79+, Firefox 103+, and Safari (with prefix). Always include both:

backdrop-filter: blur(12px);
-webkit-backdrop-filter: blur(12px);

The -webkit- prefix is required for Safari on iOS and macOS, which still needs the prefix as of 2026. For Firefox versions below 103, backdrop-filter requires the layout.css.backdrop-filter.enabled flag — it is not available to users on older Firefox without a polyfill or fallback.

Graceful degradation: provide a more opaque fallback background for browsers without support:

.glass-card {
  background: rgba(255, 255, 255, 0.85); /* fallback */
  background: rgba(255, 255, 255, 0.15); /* overridden by supporting browsers */
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

Performance Impact: GPU Compositing

backdrop-filter is an expensive operation. It forces the browser to:

1. Composite the background into an offscreen buffer
2. Apply the blur shader via the GPU
3. Composite the result back into the page

This promotes the element to its own compositing layer, which uses GPU memory. Keep these best practices in mind:

• Limit backdrop-filter to a small number of elements per page — 1–3 is typically fine, 10+ will cause noticeable frame drops on mobile
• Avoid animating the blur radius — this forces GPU recompositing every frame
• Use will-change: transform on elements that will animate near glass cards to pre-promote them to separate layers

When NOT to Use Glassmorphism

Glassmorphism is visually striking but has serious usability limitations:

• Over text-heavy backgrounds: the blurred content behind glass can make text on the card harder to read, particularly for users with low vision or in outdoor environments
• Solid color backgrounds: with no background complexity to blur, the effect looks like a plain semi-transparent card with no visual payoff
• Critical UI elements: navigation menus, form inputs, and error messages should prioritize clarity over aesthetics
• Accessibility: always ensure sufficient contrast ratio (WCAG AA minimum: 4.5:1 for body text) between card text and the blurred background, which can vary in lightness unpredictably

Complete Glassmorphism Recipe

.glass {
  background: rgba(255, 255, 255, 0.12);
  backdrop-filter: blur(14px) saturate(180%);
  -webkit-backdrop-filter: blur(14px) saturate(180%);
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow:
    0 4px 6px rgba(0, 0, 0, 0.07),
    0 12px 48px rgba(0, 0, 0, 0.1),
    inset 0 1px 0 rgba(255, 255, 255, 0.3);
  padding: 24px;
}

Adding saturate(180%) to the backdrop-filter increases the vibrancy of background colors bleeding through, enhancing the frosted glass look. The inner box-shadow (inset) simulates light reflection on the top edge of the glass surface.

Combine glassmorphism with custom shadows using our Box Shadow Generator, or add dynamic color backgrounds with the Gradient Generator.