Top Page Loading Bar
The thin glowing bar that runs along the top of the page while a route loads, the way YouTube and GitHub do it. Swap absolute for fixed to pin it to the viewport.
Also known as: NProgress bar, YouTube loading bar, GitHub loading bar.
HTML
<div class="ldr-top-bar" role="progressbar" aria-label="Page loading"></div>
CSS
.ldr-top-bar {
--s: var(--ldr-size, 48px);
--c: var(--ldr-color, #3b82f6);
position: absolute; /* use fixed to pin it to the viewport */
top: 0;
left: 0;
right: 0;
z-index: 50;
height: max(3px, calc(var(--s) / 16));
overflow: hidden;
background: color-mix(in srgb, var(--ldr-color, #3b82f6) 12%, transparent);
}
.ldr-top-bar::before {
content: "";
position: absolute;
inset: 0;
width: 30%;
border-radius: 0 999px 999px 0;
background: var(--c);
box-shadow: 0 0 10px var(--c), 0 0 4px var(--c);
animation: ldr-top-bar-run 1.4s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}
@keyframes ldr-top-bar-run {
from { transform: translateX(-100%); }
to { transform: translateX(340%); }
}
@media (prefers-reduced-motion: reduce) {
.ldr-top-bar, .ldr-top-bar *, .ldr-top-bar::before, .ldr-top-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.