CSS Animation Example: The Ken Burns Effect

The "Ken Burns Effect" is a cinematic tracking technique involving a slow, continuous pan and zoom across a static image, famously popularized by the documentary filmmaker.

Explore the Wild

To pull this off effectively on a website block (like a hero banner), structure is everything. You need a parent container with fixed dimensions and overflow: hidden to prevent the zooming image from bleeding out.

The image itself is usually applied as a background-image with background-size: cover to ensure it fits nicely regardless of screen ratio. We then apply an exceptionally long animation-duration (e.g., 15s) with an alternate direction. Inside the @keyframes, we simply drift the transform: scale() value slowly upwards to around 1.2 while providing a subtle X/Y pixel translation to simulate the panning of a camera head.

Here is the code to create The Ken Burns Effect.

<!doctype html>
<title>Example</title>
<style>
body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: sans-serif;
    background-color: #333;
}

.kb-container {
    width: 600px;
    height: 400px;
    overflow: hidden; /* Critical to crop the scaling image */
    position: relative;
    border-radius: 8px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.kb-image {
    width: 100%;
    height: 100%;
    
    /* Use a high resolution image so it doesn't pixelate when zoomed */
    background-image: url('/pix/samples/22l.jpg');
    background-size: cover;
    background-position: center;
    
    /* 
       Ensure scaling originates from roughly the center 
       so it feels like a slow push in.
    */
    transform-origin: 50% 50%;
    animation: ken-burns 15s ease-out infinite alternate;
}

/* 
    The classic effect scales slowly up and pans slightly.
    Notice we scale to 1.2 (120%) over 15 seconds.
*/
@keyframes ken-burns {
    0% {
        transform: scale(1) translate(0, 0);
    }
    100% {
        transform: scale(1.2) translate(-20px, 10px);
    }
}

/* Optional Overlay Text */
.kb-text {
    position: absolute;
    bottom: 30px;
    left: 30px;
    color: white;
    font-size: 2rem;
    font-weight: bold;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.8);
    margin: 0;
}

@media (prefers-reduced-motion: reduce) {
    .kb-image {
        animation: none; /* Just display a beautiful static image */
    }
}
</style>

<div class="kb-container">
    <div class="kb-image"></div>
    <h2 class="kb-text">Explore the Wild</h2>
</div>

View Output Full Screen Preview

Accessibility Considerations

While elegant, persistent background motion covering large areas of the screen is a common trigger for vestibular motion distress. prefers-reduced-motion is a CSS media feature used to detect if a user has enabled a setting on their device to minimize the amount of non-essential animation or motion.

Because the image itself is the primary decorative element, if a user has indicated they prefer reduced motion, you should leave the image but forcibly disable the ken-burns animation block.

Here's what we used in our example:


@media (prefers-reduced-motion: reduce) {
    .kb-image {
        /* Disables the zoom/pan, leaving a beautiful static background */
        animation: none; 
    }
}