liquid-glass

name	liquid-glass
description	Implement Apple's Liquid Glass UI effect (iOS 26 / macOS 26) using CSS and SVG displacement filters. Use this skill when asked to create liquid glass effects, frosted glass components, iOS 26 glass UI, glassmorphism with refraction, glass buttons/cards/navbars, feDisplacementMap refraction effects, or any UI that needs realistic glass-like distortion of background content. Teaches the full technique from physics (Snell's law, SDF) to ready-to-use HTML/React/CSS templates.
license	MIT
compatibility	Works in Chrome/Chromium browsers (76+) for full effect. Firefox/Safari support blur fallback.
metadata	{"author":"Zettersten","version":"1.0","docs":"https://github.com/Zettersten/skills/tree/main/skills/liquid-glass"}

Liquid Glass

Apple's Liquid Glass (iOS 26 / macOS 26) goes beyond simple backdrop-filter: blur(). It uses SVG feDisplacementMap to simulate light refraction through curved glass. Background content physically warps at the element's edges, as if viewed through real glass.

What makes it different from glassmorphism

Glassmorphism = frosted blur only. Liquid Glass = frosted blur + edge refraction (background warps near borders). The technique is backdrop-filter: url(#svg-filter) — Chrome/Chromium only for the full effect; Firefox/Safari gracefully degrade to blur.

Four-layer composition

Every Liquid Glass element stacks four layers:

<div class="glass">                    <!-- position:relative; overflow:hidden -->
  <div class="glass__refract"></div>   <!-- Layer 0: backdrop-filter + SVG filter -->
  <div class="glass__tint"></div>      <!-- Layer 1: semi-transparent color tint -->
  <div class="glass__specular"></div>  <!-- Layer 2: inset box-shadow rim highlight -->
  <div class="glass__content">...</div><!-- Layer 3: your actual content -->
</div>

.glass { position: relative; border-radius: 28px; overflow: hidden; }

/* Layer 0: Refraction (Chrome only for SVG filter URL) */
.glass__refract {
  position: absolute; inset: 0; border-radius: inherit;
  backdrop-filter: blur(12px) url(#liquid-glass) brightness(1.05) saturate(1.3);
  -webkit-backdrop-filter: blur(12px) url(#liquid-glass) brightness(1.05) saturate(1.3);
  isolation: isolate;   /* REQUIRED — creates stacking context */
}

/* Layer 1: Glass tint */
.glass__tint {
  position: absolute; inset: 0; border-radius: inherit;
  background: rgba(255, 255, 255, 0.18);
}

/* Layer 2: Specular rim (top edge bright, bottom edge subtle) */
.glass__specular {
  position: absolute; inset: 0; border-radius: inherit;
  box-shadow:
    inset     (,,,),
    inset  -  (,,,);
}


 { : relative; : ; }

SVG filter (the refraction engine)

Define once in a hidden <svg> anywhere in the DOM:

<svg xmlns="http://www.w3.org/2000/svg" width="0" height="0"
     style="position:absolute;overflow:hidden">
  <defs>
    <filter id="liquid-glass" color-interpolation-filters="sRGB"
            x="0%" y="0%" width="100%" height="100%">
      <feImage result="dispMap"
        x="0" y="0" width="ELEMENT_WIDTH" height="ELEMENT_HEIGHT"
        preserveAspectRatio="none"
        href="DISPLACEMENT_MAP_DATA_URI"
      />
      <feDisplacementMap
        in="SourceGraphic" in2="dispMap"
        scale="-35"
        xChannelSelector="R" yChannelSelector="G"
      />
    </filter>
  </defs>

scale is the key parameter: negative = magnifying (Apple-style), positive = fish-eye.

Displacement map — the key concept

The displacement map is an image where color = movement instruction:

• R channel = horizontal shift (128 = neutral, 255 = max right, 0 = max left)
• G channel = vertical shift (128 = neutral, 255 = max down, 0 = max up)
• scale amplifies: actual_px = (channel/255 - 0.5) × scale

Edge pixels have non-neutral R/G → sample content from slightly inward → looks like refracted glass. Center pixels have R=G=128 → no displacement → flat glass surface.

Workflow

Path A — Copy a pre-baked template (fastest) Ready-to-use files in assets/templates/:

• glass-button.html — 300×56 pill CTA button, vivid demo background
• glass-card.html — 360×220 card with full chromatic aberration
• glass-pill-navbar.html — Apple-style 3-item tab bar with nested active state
• LiquidGlass.tsx — React/TypeScript component (React 18+, no external dependencies)

Open any HTML file in Chrome to see the full effect.

Path B — Generate a custom displacement map For elements with non-standard dimensions or physics-precise refraction:

python scripts/generate-displacement-map.py \
  --width 400 --height 80 --radius 40 \
  --mode sdf --output map.png --datauri

Copy the printed data URI into <feImage href="...">. Two modes: sdf (fast, great results) and snell (physics-accurate Snell's law).

Key parameters

Parameter	What it does	Range
scale on feDisplacementMap	Refraction strength. Negative = magnify.	-20 (subtle) to -50 (dramatic)
blur in backdrop-filter	Frosted glass thickness	8–20px
tint layer background	Glass color + opacity	rgba(255,255,255, 0.12–0.25)
specular top box-shadow alpha	Rim highlight brightness	0.5–0.9

Browser compatibility

Full effect: Chrome 76+ / Edge 79+ (Chromium) only. Fallback (blur only): All modern browsers — Firefox/Safari ignore the url() part automatically, keeping the blur.

/* No @supports needed — automatic graceful degradation */
backdrop-filter: blur(12px) url(#liquid-glass) brightness(1.05) saturate(1.3);
/* Firefox/Safari see: blur(12px) brightness(1.05) saturate(1.3) ✓ */
/* Chrome sees full pipeline ✓ */

Chromatic aberration (advanced)

Run three feDisplacementMap passes (R/G/B) with slightly different scale values (±5–7%), isolate each channel with feColorMatrix, merge with feBlend mode="screen". See assets/templates/glass-card.html for a complete working example.

Learn more

• Physics deep-dive (Snell's law, SDF, surface functions, pitfalls): references/physics.md
• SVG filter primitives A–Z, pipeline, browser compat, performance: references/filter-pipeline.md
• Generator script usage: python scripts/generate-displacement-map.py --help