Skip to content
My cat wrote this blog.

Building Apple's Liquid Glass Effect for Web

9/19/2025
#ui#effects#liquid-glass#css#svg

The Story Begins

So there I was, scrolling through iOS 26's new Liquid Glass effects, and my first thought was: "That's gorgeous... but how the heck does it work?"

You know that feeling when you see something so visually satisfying that you immediately want to recreate it? That was me, staring at Apple's liquid glass interface while my cat settled in for another vibe-coding session.

The effect isn't just "make it transparent"—there's actual physics happening. Light bends, colors split, edges sparkle. It's like looking through actual liquid glass, and somehow Apple made it feel... alive.

So naturally, we spent the next few days figuring out how to build it for the web. Spoiler alert: SVG filters are wild.

Wait, Why Does Glass Look So Cool Anyway?

Before diving into code, let's think about what makes glass special. It's not just "transparent thing goes brrr."

Grab a glass of water, hold it up to a window, and watch the magic:

  1. Everything warps slightly - Light bends as it passes through, making backgrounds curve
  2. Edges get extra sparkly - Light concentrates at the boundaries (hello, rim lighting!)
  3. Tiny rainbows appear - Different colors bend at slightly different angles (chromatic aberration)
  4. Highlights dance around - Reflections change based on your viewing angle

These aren't just pretty accidents—they're physics in action. And lucky for us, we can fake most of this with some clever SVG tricks.

Breaking It Down: The Four Elements of Liquid Glass

🪟 1) Interior - The "Glass Thickness" Vibe

Goal: That subtle "looking through glass" feeling without being too obvious.

  • Blur: Makes the background slightly soft, like glass has actual thickness
  • Tiny warping: Just enough distortion to feel "glassy" without being distracting
  • Keep it consistent: The interior should feel uniform and natural

The goldilocks zone: Too strong and you get magnifying glass. Too weak and it's just... transparent. Getting it just right is the secret sauce.

✨ 2) Edges - Where the Magic Happens

Goal: Heavy distortion at the borders, because that's where glass gets dramatic.

  • Strong refraction: Think magnifying glass vibes—backgrounds stretch and curve
  • Chromatic aberration: Red, green, blue channels split slightly for that "real glass" look
  • Gradual transition: Effect gets stronger as you move from center to edge

Think of it like: Looking through a marble or the edge of a drinking glass—everything gets beautifully warped.

🎨 3) Lighting Effects - The Sparkle Factor

Goal: Make it shine like actual glass catching light.

Fresnel Effect (Edge Glow)

  • Rim lighting: Edges naturally get brighter based on viewing angle
  • Soft sparkle: That gentle glow around the entire border
  • Physics-based: It's a real optical phenomenon, not just decoration

Specular Highlights (The Sharp Glints)

  • Mirror-like reflections: Sharp, bright spots where light bounces off
  • Gradient magic: We'll use SVG to turn smooth gradients into crisp light streaks
  • Fixed positioning: Real glass would move these highlights dynamically, but we'll cheat with a diagonal pattern

Alright, enough theory. Time to get our hands dirty with SVG filters and make some digital glass magic happen.

Step 1: Interior (The Foundation)

Making Glass Feel Like Glass

To nail that "looking through glass" vibe, we need two ingredients:

  1. Blur: Gives the sense of thickness and depth
  2. Subtle warping: Just enough distortion to feel organic

Here's the plan: use SVG filters to add gentle blur and tiny displacement. The feTurbulence + feDisplacementMap combo creates natural-looking warping, while feGaussianBlur handles the softness.

The Key Numbers (What They Actually Do)

  • stdDeviation="1.5": Blur intensity. Too high = muddy mess, too low = barely noticeable
  • baseFrequency="0.010": Noise detail level. Higher = busy texture, lower = smooth waves
  • scale="30": Distortion strength. Negative = magnifying glass, positive = fish-eye lens
<feGaussianBlur
  in="SourceGraphic" stdDeviation="1.5" result="blur"
/>
<feTurbulence
  type="fractalNoise" baseFrequency="0.010" numOctaves="1" seed="7" result="noise"
/>
<feDisplacementMap
  in="blur" in2="noise" scale="30" xChannelSelector="R" yChannelSelector="G" result="disp"
/>
<feBlend
  in="disp" in2="SourceGraphic" mode="normal" result="blended"
/>
BACKGROUND
TEXT LAYER

See that? The cat image in the background gets slightly fuzzy and subtly warped—that's the natural "looking through glass" effect we're after!

💡 Pro Tips

Performance stuff:

  • feTurbulence is expensive! Keep that seed value fixed so it doesn't recalculate constantly
  • Too high baseFrequency = laggy animations (learned this the hard way)

Design notes:

  • Solid backgrounds make the effect invisible—always test with patterns or images
  • On mobile, dial down the blur intensity or your users will think their phone is broken

Step 2: Edges (Where Things Get Weird)

Why Edges Matter

Real glass gets its drama from the edges. That's where the thickness changes and light goes absolutely wild with refraction. To recreate this digitally, we need something called a "refraction map"—basically a special texture that tells each pixel how to bend.

Building a Refraction Map

Think of a refraction map as a instruction manual for light bending. Red channel controls X-axis warping, Green handles Y-axis—it's like a GPS for photons.

Our game plan:

  • Edges: Red/Green gradients create strong distortion
  • Center: Gray (#808080) keeps things calm
  • Blur: Smooth transitions so it doesn't look like a glitch

We're creating a map where the edges have strong red/green gradients for maximum warping, while the center stays neutral gray. A bit of blur makes everything blend naturally instead of looking like broken graphics.

<feImage
  href={`data:image/svg+xml,${encodeURIComponent(`
    <svg width='100%' height='100%' viewBox='0 0 100 100' xmlns='http://www.w3.org/2000/svg'>
      <defs>
        <linearGradient id='gradient1' x1='0%' y1='0%' x2='100%' y2='0%'>
          <stop offset='0%' stop-color='#000'/>
          <stop offset='100%' stop-color='#F00'/>
        </linearGradient>
        <linearGradient id='gradient2' x1='0%' y1='0%' x2='0%' y2='100%'>
          <stop offset='0%' stop-color='#000'/>
          <stop offset='100%' stop-color='#0F0'/>
        </linearGradient>
        <filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.010' numOctaves='1' seed='7'/></filter>
      </defs>
      <rect x='0' y='0' width='100%' height='100%' fill='url(#gradient1)' style='mix-blend-mode:screen'/>
      <rect x='0' y='0' width='100%' height='100%' fill='url(#gradient2)' style='mix-blend-mode:screen'/>
      <rect width='100%' height='100%' filter='url(#n)' style='mix-blend-mode:overlay'/>
      <rect x='0' y='0' width='100%' height='100%' fill='#808080BB' style='filter:blur(10px)'/>
    </svg>
  `)}`}
  x="0%"
  y="0%"
  width="100%"
  height="100%"
  result="refractMap"
/>
BACKGROUND
TEXT LAYER

Look at that! Red and green gradients at the edges, neutral gray in the center—that's our refraction map ready to wreak some beautiful havoc.

Putting the Map to Work

Now we feed this map to feDisplacementMap to actually bend the pixels:

  • xChannelSelector="R": Red channel warps horizontally
  • yChannelSelector="G": Green channel warps vertically
  • scale="-130": How intense the warping gets (negative = magnifying, positive = shrinking)

💡 Scale values decoded:

  • -130: Magnifying glass effect (everything looks bigger)
  • +130: Fish-eye lens effect (everything squishes inward)
  • 0: No warping (boring but stable)
<feGaussianBlur
  in="SourceGraphic" stdDeviation="1.5" result="blur"
/>
<feDisplacementMap
  in="blur" in2="refractMap" scale="-130" xChannelSelector="R" yChannelSelector="G" result="disp"
/>
<feBlend
  in="disp" in2="SourceGraphic" mode="normal" result="blended"
/>
BACKGROUND
TEXT LAYER

Perfect! Now the background bends at the edges like we're looking through an actual lens.

Adding Chromatic Aberration (The Rainbow Edge Effect)

Here's where we get fancy. Real glass and lenses don't bend all colors equally—red, green, and blue light each has its own refraction angle. This creates those subtle rainbow fringes you see on camera lenses and cheap glasses.

The plan:

  1. Apply different warp strengths to each RGB channel
  2. Use feColorMatrix to isolate each color
  3. Blend them back together with feBlend

Why different scale values?

  • Red (-130): Baseline warping
  • Green (-136): Slightly more aggressive
  • Blue (-133): Right in the middle

These tiny differences make each color bend slightly differently, creating that authentic chromatic aberration that screams "real glass."

<feGaussianBlur
  in="SourceGraphic" stdDeviation="1.5" result="blur"
/>
<feDisplacementMap
  in="blur" in2="refractMap" scale="-130" xChannelSelector="R" yChannelSelector="G" result="dispR"
/>
<feColorMatrix
  in="dispR" type="matrix"
  values="
  1 0 0 0 0
  0 0 0 0 0
  0 0 0 0 0
  0 0 0 1 0"
  result="Ronly"
/>
<feDisplacementMap
  in="blur" in2="refractMap" scale="-140" xChannelSelector="R" yChannelSelector="G" result="dispG"
/>
<feColorMatrix
  in="dispG" type="matrix"
  values="
  0 0 0 0 0
  0 1 0 0 0
  0 0 0 0 0
  0 0 0 1 0"
  result="Gonly"
/>
<feDisplacementMap
  in="blur" in2="refractMap" scale="-135" xChannelSelector="R" yChannelSelector="G" result="dispB"
/>
<feColorMatrix
  in="dispB" type="matrix"
  values="
  0 0 0 0 0
  0 0 0 0 0
  0 0 1 0 0
  0 0 0 1 0"
  result="Bonly"
/>
<feBlend in="Ronly" in2="Gonly" mode="screen" result="RG" />
<feBlend in="RG" in2="Bonly" mode="screen" result="RGB_CA" />
BACKGROUND
TEXT LAYER

What we just did:

  • Edge warping: Created a refraction map with gradients and blur, then used feDisplacementMap to separate center (mild warping) from edges (dramatic lens effect)
  • Color separation: Split R/G/B channels with slightly different displacement values, isolated them with feColorMatrix, then blended back with screen mode for realistic edge color fringing

Step 3: Fresnel Effect (The Edge Glow)

What's This Fresnel Thing?

Back in 1818, French physicist Augustin-Jean Fresnel figured out why glass looks different depending on your viewing angle. It's physics, but the gist is:

  • Look straight at glass: Mostly transparent (light passes through)
  • Look at an angle: Gets reflective and bright (light bounces back)

This is why water surfaces and glass edges seem to glow when you're not looking at them head-on. Pretty cool, right?

Faking Fresnel with SVG

Real Fresnel calculations involve trigonometry and tears. SVG lets us cheat by creating a mask that just makes edges bright. Way easier, almost as convincing.

The strategy:

  1. feMorphology(erode): Carve out the inside of our shape
  2. feGaussianBlur: Soften those harsh carved edges
  3. feComposite(out): Subtract the carved part from the original, leaving just the rim

We're basically creating a soft edge mask using morphology filters to eat away at the center, then blurring it smooth.

<feImage
  href={`data:image/svg+xml,${encodeURIComponent(`
    <svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'>
        <defs>
            <filter id='fresnelPipeline' x='-50%' y='-50%' width='200%' height='200%' color-interpolation-filters='sRGB'>
            <feMorphology in='SourceGraphic' operator='erode' radius='6' result='inset'/>
            <feGaussianBlur in='inset' stdDeviation='5.5' result='fresnelMask'/>
            </filter>
        </defs>
        <rect x='0' y='0' width='100' height='100' rx='10' fill='white' filter='url(#fresnelPipeline)'/>
    </svg>
  `)}`}
  x="0%"
  y="0%"
  width="100%"
  height="100%"
  preserveAspectRatio="none"
  result="fresnelMask"
/>
<feComposite
  in="SourceGraphic" in2="fresnelMask" operator="out" result="fresnelMask"
/>
<feBlend
  in="fresnelMask" in2="SourceGraphic" mode="screen" result="blended"
/>
BACKGROUND
TEXT LAYER

Beautiful! Only the edges are bright while the center stays dark—that's our Fresnel mask ready to make some rim lighting magic.

Applying the Highlight

Now we use this mask to add bright highlights only to the edges. feFlood creates pure white, and feComposite constrains it to just the mask area.

<feFlood
  flood-color="white" flood-opacity="1.0" result="color"
/>
<feComposite
  in="color" in2="fresnelMask" operator="in" result="bright"
/>
<feBlend
  in="bright" in2="blended" mode="screen" result="blended"
/>
BACKGROUND
TEXT LAYER

What just happened:

  • Edge mask creation: Used feMorphology(erode) to carve out the center, then feComposite(out) to create our rim mask
  • Highlight application: Blended the result with feBlend(mode="screen") to enhance that edge sparkle

Step 4: Specular Highlights (The Sharp Glints)

Why Glass Gets Those Sharp Glints

Smooth surfaces like glass and metal create specular reflections—mirror-like bounces where the angle of incoming light equals the angle of reflected light. Basic physics, fancy results.

In the real world, highlights depend on:

  • Light source position: Where the light's coming from
  • Surface curvature: How the glass curves and bends
  • Viewing angle: Where you're looking from

All these factors combine to create those sharp, bright spots that make glass look... glassy.

Approximating with SVG

Real physics involves calculus and headaches. SVG lets us fake it with assumed light sources and fixed viewpoints—way simpler, still impressive.

Our approach:

  1. Diagonal gradient: Fake a light source coming from bottom-left to top-right
  2. ComponentTransfer: Transform smooth gradients into sharp highlights
  3. Combine with Fresnel mask: Limit highlights to edge areas only

Since calculating actual light-surface interactions in SVG would drive us insane, we're cheating with a diagonal gradient that mimics light direction. The trick is using ComponentTransfer to turn that smooth gradient into a sharp, bright streak that actually looks like reflected light.

<feImage
  href={`data:image/svg+xml,${encodeURIComponent(`
    <svg viewBox='0 0 100 100' xmlns='http://www.w3.org/2000/svg'>
      <defs>
        <linearGradient id='g' x1='0' y1='100%' x2='100%' y2='0'>
          <stop offset='0' stop-color='white' stop-opacity='1'/>
          <stop offset='0.3' stop-color='black' stop-opacity='0'/>
          <stop offset='0.7' stop-color='black' stop-opacity='0'/>
          <stop offset='1' stop-color='white' stop-opacity='1'/>
        </linearGradient>
      </defs>
      <rect x='0' y='0' width='100%' height='100%' fill='url(#g)'/>
    </svg>
    `)}`}
  x="0"
  y="0"
  width="100%"
  height="100%"
  result="lightDir"
/>
<feComponentTransfer in="lightDir" result="lightCurve">
  <feFuncA type="gamma" amplitude="2" exponent="5.0" offset="0" />
</feComponentTransfer>
<feComposite
  in="lightCurve"
  in2="fresnelMask"
  operator="in"
  result="lightMask"
/>
<feBlend
  in="SourceGraphic"
  in2="lightMask"
  mode="screen"
  result="withGlare"
/>
BACKGROUND
TEXT LAYER

Boom! See that sharp diagonal highlight? It actually looks like light reflecting off real glass. Not bad for some fake math!

The ComponentTransfer Magic

The secret sauce is feComponentTransfer:

<feFuncA type="gamma" amplitude="2" exponent="5.0" offset="0" />
  • amplitude="2": Cranks up max brightness by 2x
  • exponent="5.0": Creates an aggressive curve that drops off quickly
  • Result: Smooth gradient → razor-sharp highlight

This transform turns a boring linear gradient into something that actually mimics how light behaves on glass surfaces—sharp, intense, and totally convincing.

💡 Customization Tips

Sharper highlights: Pump exponent to 8.0 or higher Softer highlights: Dial exponent down to 2.0-3.0 Different angles: Adjust the gradient's x1, y1, x2, y2 values

The Grand Finale: All Effects Combined

Time to bring everything together and see the magic happen:

  1. Interior: Subtle blur and micro-warping for depth
  2. Edges: Dramatic refraction with chromatic aberration
  3. Fresnel: Rim lighting that sparkles at the borders
  4. Highlights: Sharp glints that catch the light

When all these effects work in harmony...

BACKGROUND
TEXT LAYER

🎉 BAM! Now THAT looks like actual glass! The background warps naturally, edges sparkle with Fresnel glow and sharp highlights, and chromatic aberration adds that final touch of realism. Solid vibe-coding session right there.

Real-World Implementation Guide

Cool demos are fun, but let's talk about actually using this stuff in production without getting fired.

🚀 Performance Reality Check

Filter complexity management:

  • Don't use all effects at once—pick your top 2-3 favorites and call it a day

⚡ Better Alternatives (For When You Get Ambitious)

Canvas/WebGL upgrades:

  • Interactive highlights: Mouse-following glints that actually respond to user movement
  • Dynamic refraction: Warping that changes with scroll or animation
  • Physics-based rendering: Three.js MeshPhysicalMaterial for mathematically accurate Fresnel
  • Performance: GPU acceleration for butter-smooth 60fps animations

🌟 Wrapping Up

And there you have it—liquid glass on the web! Our cat just pulled off another successful vibe-coding project.

The key takeaways:

  • Physics matters: Understanding real glass behavior makes fake glass look convincing
  • Layer by layer: Interior → Edges → Fresnel → Highlights. Each step builds on the last
  • Performance is king: SVG filters are powerful but can be heavy—use them wisely

Now go forth and make the web a more liquid, glassy place. Happy vibe-coding! 🎉