Rotating Square Fill Button
A square spins a three-eighths turn while it grows from the center, landing square-on to cover the button. One transform on one pseudo-element, with a fast-out easing so it lands softly.
Also known as: spin fill button, rotate in fill hover, twist fill button.
HTML
<button class="hfx-rotating-square-fill">Create account</button>
CSS
.hfx-rotating-square-fill {
--c: var(--hfx-color, #3b82f6);
position: relative;
isolation: isolate;
overflow: hidden;
display: inline-flex;
align-items: center;
justify-content: center;
gap: 0.5em;
padding: 0.75em 1.75em;
border-radius: 0.5em;
font: 600 var(--hfx-size, 16px)/1.2 system-ui, sans-serif;
white-space: nowrap;
cursor: pointer;
border: 2px solid var(--c);
background: transparent;
color: var(--c);
transition: color 0.3s ease 0.1s;
}
.hfx-rotating-square-fill::before {
content: "";
position: absolute;
left: 50%;
top: 50%;
z-index: -1;
width: 110%;
aspect-ratio: 1;
background: var(--c);
transform: translate(-50%, -50%) rotate(-135deg) scale(0);
transition: transform 0.6s cubic-bezier(0.22, 1, 0.36, 1);
}
.hfx-rotating-square-fill:is(:hover, :focus-visible) {
background-color: var(--c); /* hides the hairline where the fill meets the border */
color: #fff;
transition: color 0.3s ease 0.1s, background-color 0s 0.6s;
}
.hfx-rotating-square-fill:is(:hover, :focus-visible)::before {
transform: translate(-50%, -50%) rotate(0) scale(1);
}
@media (prefers-reduced-motion: reduce) {
.hfx-rotating-square-fill, .hfx-rotating-square-fill *, .hfx-rotating-square-fill::before, .hfx-rotating-square-fill::after, .hfx-rotating-square-fill *::before, .hfx-rotating-square-fill *::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
}
}Customizing this snippet
- Color: set
--hfx-coloron the element or a parent. Currently previewing#3b82f6. - Base size: set
--hfx-size. Every other dimension is inem, so the whole thing scales together. Currently previewing16px. - Speed: change the duration on the
transitionoranimationshorthand. Staggered delays are relative, so they keep their rhythm. - Reduced motion: the rule at the end of the CSS turns the motion off for people who asked their OS for less of it. Keep it.