Shimmer Progress Bar
A squared-off install bar that steps forward with a slight spring while a band of light keeps running through the filled part, the way desktop installers show they are still alive.
Also known as: windows progress bar, shine progress bar, glossy loading bar.
HTML
<div class="ldr-shimmer-progress-bar" role="progressbar" aria-label="Loading"><span></span></div>
CSS
.ldr-shimmer-progress-bar {
--s: var(--ldr-size, 48px);
--c: var(--ldr-color, #3b82f6);
width: calc(var(--s) * 6);
height: calc(var(--s) / 4);
border-radius: calc(var(--s) / 16);
background: color-mix(in srgb, var(--ldr-color, #3b82f6) 12%, transparent);
box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--ldr-color, #3b82f6) 24%, transparent);
overflow: hidden;
}
.ldr-shimmer-progress-bar span {
position: relative;
display: block;
height: 100%;
overflow: hidden;
background: linear-gradient(color-mix(in srgb, var(--c) 80%, #fff), var(--c) 55%, color-mix(in srgb, var(--c) 85%, #000));
transform-origin: left;
animation: ldr-shimmer-progress-bar-fill 5s infinite;
}
.ldr-shimmer-progress-bar span::after {
content: "";
position: absolute;
top: 0;
bottom: 0;
left: 0;
width: 40%;
background: linear-gradient(90deg, transparent, rgb(255 255 255 / 0.6), transparent);
transform: translateX(-100%);
animation: ldr-shimmer-progress-bar-shine 1.5s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}
@keyframes ldr-shimmer-progress-bar-fill {
0% { transform: scaleX(0); animation-timing-function: cubic-bezier(0.34, 1.4, 0.64, 1); }
10%, 26% { transform: scaleX(0.22); animation-timing-function: cubic-bezier(0.34, 1.4, 0.64, 1); }
36%, 52% { transform: scaleX(0.48); animation-timing-function: cubic-bezier(0.34, 1.4, 0.64, 1); }
62%, 72% { transform: scaleX(0.74); animation-timing-function: cubic-bezier(0.34, 1.2, 0.64, 1); }
82%, 94% { transform: scaleX(1); opacity: 1; }
100% { transform: scaleX(1); opacity: 0; }
}
@keyframes ldr-shimmer-progress-bar-shine {
70%, 100% { transform: translateX(260%); }
}
@media (prefers-reduced-motion: reduce) {
.ldr-shimmer-progress-bar, .ldr-shimmer-progress-bar *, .ldr-shimmer-progress-bar::before, .ldr-shimmer-progress-bar::after, .ldr-shimmer-progress-bar *::before, .ldr-shimmer-progress-bar *::after {
animation-duration: 3s;
}
}Customizing this loader
- Color: set
--ldr-coloron the element or a parent. Currently previewing#3b82f6. - Size: set
--ldr-size. Every dimension in the snippet is derived from it. Currently previewing64px. - Speed: change the duration on the
animationshorthand. Delays on the children are relative, so they keep their rhythm. - Accessibility: the root carries
role="status"and anaria-labelso screen readers announce the wait. The reduced-motion rule at the end slows the animation for users who asked for less motion.