Round Corners Hover Effect
A square-cornered button softens into a pill on hover. Only border-radius transitions; it is set a touch past half the height so the ends end up fully round at any font size.
Also known as: hvr-round-corners, border radius transition, square to pill button.
HTML
<button class="hfx-round-corners">Sign up free</button>
CSS
.hfx-round-corners {
--c: var(--hfx-color, #3b82f6);
display: inline-flex;
align-items: center;
gap: 0.5em;
padding: 0.7em 1.6em;
border-radius: 0.5em;
font: 600 var(--hfx-size, 16px) system-ui, sans-serif;
cursor: pointer;
border: 0;
background: var(--c);
color: #fff;
border-radius: 0;
transition: border-radius 0.35s cubic-bezier(0.25, 0.8, 0.25, 1);}
.hfx-round-corners:is(:hover, :focus-visible) {
border-radius: 1.4em;
}
@media (prefers-reduced-motion: reduce) {
.hfx-round-corners, .hfx-round-corners *, .hfx-round-corners::before, .hfx-round-corners::after, .hfx-round-corners *::before, .hfx-round-corners *::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
}
}Tailwind CSS version
The same effect using Tailwind utility classes. No custom CSS or config needed.
<button class="rounded-none bg-blue-500 px-6 py-3 font-semibold text-white transition-[border-radius] duration-300 ease-out hover:rounded-3xl focus-visible:rounded-3xl"> Sign up free </button>
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.