CSS Animation Example: The Skeleton Wave

The "Skeleton Wave" (or shimmer) is a modern loading pattern that displays a simplified mockup of the content layout while the actual data fetches.

This animation creates the illusion of a light beam sweeping across the elements. We achieve this by giving each placeholder element a solid base color and overlaying it with a semi-transparent linear gradient (linear-gradient()). We use background-size: 200% to make the gradient larger than the element, and then animate its background-position from left to right using @keyframes.

Here is the code to create the Skeleton Wave animation.

<!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: #f0f0f0;
}

.skeleton-card {
    width: 300px;
    padding: 20px;
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.skeleton-line {
    height: 15px;
    margin-bottom: 10px;
    border-radius: 4px;
    background-color: #e2e5e7;
    /* The gradient is twice as wide as the element to allow it to slide across */
    background-image: linear-gradient(
        90deg,
        rgba(255, 255, 255, 0),
        rgba(255, 255, 255, 0.5),
        rgba(255, 255, 255, 0)
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite linear;
}

.skeleton-line:last-child {
    width: 60%;
    margin-bottom: 0;
}

.skeleton-avatar {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    margin-bottom: 15px;
    background-color: #e2e5e7;
    background-image: linear-gradient(90deg, rgba(255, 255, 255, 0), rgba(255, 255, 255, 0.5), rgba(255, 255, 255, 0));
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite linear;
}

@keyframes shimmer {
    0% { background-position: -200% 0; }
    100% { background-position: 200% 0; }
}

@media (prefers-reduced-motion: reduce) {
    .skeleton-line, .skeleton-avatar {
        animation: none;
        background-image: none;
    }
}
</style>

View Output

Accessibility Considerations

Rapid, high-contrast flashing can be an issue, but a soft, slow shimmer is generally well-tolerated. However, it's safest to respect the prefers-reduced-motion media query by removing the animation entirely for users who have requested their system minimize non-essential motion.

A static skeleton screen still effectively communicates that content is loading without relying on movement. Here's how we handled it in our code example:


@media (prefers-reduced-motion: reduce) {
    .skeleton-line, .skeleton-avatar {
        animation: none;
        background-image: none; /* Remove the gradient so it's a solid block */
    }
}