Filling Square Loader
A square outline flips over empty, fills from the bottom, flips again while full, then drains. The classic hourglass square, redone with scaleY and a swapped transform-origin instead of height.
Also known as: square fill loader, hourglass square loader, rotating fill square.
HTML
<div class="ldr-filling-square" role="status" aria-label="Loading"></div>
CSS
.ldr-filling-square {
--s: var(--ldr-size, 48px);
--c: var(--ldr-color, #3b82f6);
width: calc(var(--s) * 0.8);
height: calc(var(--s) * 0.8);
margin: calc(var(--s) * 0.1);
padding: calc(var(--s) / 24);
border: calc(var(--s) / 14) solid var(--c);
border-radius: calc(var(--s) / 20);
animation: ldr-filling-square-flip 2.4s cubic-bezier(0.7, 0, 0.3, 1) infinite;
}
.ldr-filling-square::before {
content: "";
display: block;
width: 100%;
height: 100%;
border-radius: calc(var(--s) / 60);
background: var(--c);
animation: ldr-filling-square-fill 2.4s cubic-bezier(0.45, 0, 0.55, 1) infinite;
}
@keyframes ldr-filling-square-flip {
0% { transform: rotate(0deg); }
25%, 50% { transform: rotate(180deg); }
75%, 100% { transform: rotate(360deg); }
}
@keyframes ldr-filling-square-fill {
0%, 25% { transform: scaleY(0); transform-origin: 50% 0; }
50% { transform: scaleY(1); transform-origin: 50% 0; }
75% { transform: scaleY(1); transform-origin: 50% 100%; }
100% { transform: scaleY(0); transform-origin: 50% 100%; }
}
@media (prefers-reduced-motion: reduce) {
.ldr-filling-square, .ldr-filling-square *, .ldr-filling-square::before, .ldr-filling-square::after, .ldr-filling-square *::before, .ldr-filling-square *::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.