Flash
The element blinks out and back twice in quick succession, then stays lit. A classic way to point at something that just changed, like a new total or a saved field. Opacity only.
Also known as: flash animation css, flashing element, double flash.
Flash
HTML
<div class="kfa-flash">Flash</div>
CSS
.kfa-flash {
--c: var(--kfa-color, #3b82f6);
font-size: var(--kfa-size, 16px);
display: grid;
place-items: center;
width: 5.5em;
height: 5.5em;
border-radius: 1em;
background: var(--c);
color: #fff;
font-family: system-ui, sans-serif;
font-weight: 700;
box-shadow: 0 0.6em 1.4em -0.6em color-mix(in srgb, var(--c) 70%, transparent);
animation: kfa-flash-strobe 1s ease-in-out both;
}
@keyframes kfa-flash-strobe {
0%, 30%, 60%, 100% { opacity: 1; }
15%, 45% { opacity: 0; }
}
@media (prefers-reduced-motion: reduce) {
.kfa-flash, .kfa-flash *, .kfa-flash::before, .kfa-flash::after, .kfa-flash *::before, .kfa-flash *::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
}
}Customizing this snippet
- Color: set
--kfa-coloron the element or a parent. Currently previewing#3b82f6. - Base size: set
--kfa-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.