Paint Drip Button: CSS Hover Effect

Paint Drip Button

A lip of wet paint with a few drips hangs from the top edge; on hover the paint pours down and fills the button. Drips and sags are gradient layers on one pseudo-element that only moves.

Also known as: dripping paint hover, melting fill button, drip effect css.

Color Base size 16px Dark background Hold hover state

HTML

<button class="hfx-paint-drip">Start a project</button>

CSS

.hfx-paint-drip {
  --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 0.15s;
}
.hfx-paint-drip::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: -1;
  height: calc(100% + 1em);
  background:
    linear-gradient(var(--c) 0 0) 0 0 / 100% calc(100% - 1em),
    radial-gradient(closest-side, var(--c) 96%, transparent) left 24% bottom 0.82em / 2em 0.36em,
    radial-gradient(closest-side, var(--c) 96%, transparent) left 52% bottom 0.87em / 1.3em 0.26em,
    radial-gradient(closest-side, var(--c) 96%, transparent) left 76% bottom 0.8em / 2.2em 0.4em,
    linear-gradient(var(--c) 0 0) 7% 0 / 0.5em calc(100% - 0.4em),
    radial-gradient(closest-side, var(--c) 96%, transparent) left 7% bottom 0.15em / 0.5em 0.5em,
    linear-gradient(var(--c) 0 0) 38% 0 / 0.34em calc(100% - 0.79em),
    radial-gradient(closest-side, var(--c) 96%, transparent) left 38% bottom 0.62em / 0.34em 0.34em,
    linear-gradient(var(--c) 0 0) 92% 0 / 0.42em calc(100% - 0.61em),
    radial-gradient(closest-side, var(--c) 96%, transparent) left 92% bottom 0.4em / 0.42em 0.42em;
  background-repeat: no-repeat;
  transform: translateY(calc(-100% + 1.3em));
  transition: transform 0.6s cubic-bezier(0.55, 0, 0.25, 1);
}
.hfx-paint-drip:is(:hover, :focus-visible) {
  background-color: var(--c); /* hides the hairline where the fill meets the border */
  color: #fff;
  transition: color 0.3s ease 0.15s, background-color 0s 0.6s;
}
.hfx-paint-drip:is(:hover, :focus-visible)::before { transform: translateY(0); }

@media (prefers-reduced-motion: reduce) {
  .hfx-paint-drip, .hfx-paint-drip *, .hfx-paint-drip::before, .hfx-paint-drip::after, .hfx-paint-drip *::before, .hfx-paint-drip *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

Customizing this snippet

Color: set --hfx-color on the element or a parent. Currently previewing #3b82f6.
Base size: set --hfx-size. Every other dimension is in em, so the whole thing scales together. Currently previewing 16px.
Speed: change the duration on the transition or animation shorthand. 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.

Paint Drip Button

HTML

CSS

Customizing this snippet

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