Offset Gradient Border
A gradient outline floats just off a white box and circles behind it, peeking out one side at a time like a misprinted layer. One transform keyframe of rotate, translate, rotate back moves it.
Also known as: offset border animation css, floating outline border, shifted border css.
Offset border
HTML
<div class="bdr-offset-gradient-border">Offset border</div>
CSS
.bdr-offset-gradient-border {
--c: var(--bdr-color, #3b82f6);
font-size: var(--bdr-size, 16px);
position: relative;
display: grid;
place-items: center;
width: 15em;
height: 8.5em;
border-radius: 1em;
font-family: system-ui, sans-serif;
font-weight: 600;
isolation: isolate;
color: #111827;
}
.bdr-offset-gradient-border::before,
.bdr-offset-gradient-border::after {
content: "";
position: absolute;
inset: 0;
z-index: -1;
border-radius: inherit;
pointer-events: none;
}
.bdr-offset-gradient-border::before {
padding: 0.18em;
background: linear-gradient(135deg, var(--c), color-mix(in oklch, var(--c), #ec4899 80%), color-mix(in oklch, var(--c), #f59e0b 75%));
-webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
-webkit-mask-composite: xor;
mask: linear-gradient(#000 0 0) content-box exclude, linear-gradient(#000 0 0);
animation: bdr-offset-gradient-border-orbit 4s linear infinite;
}
.bdr-offset-gradient-border::after {
background: #fff;
box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--c) 25%, #cbd5e1);
}
@keyframes bdr-offset-gradient-border-orbit {
from { transform: rotate(0turn) translate(0.55em) rotate(0turn); }
to { transform: rotate(1turn) translate(0.55em) rotate(-1turn); }
}
@media (prefers-reduced-motion: reduce) {
.bdr-offset-gradient-border, .bdr-offset-gradient-border *, .bdr-offset-gradient-border::before, .bdr-offset-gradient-border::after, .bdr-offset-gradient-border *::before, .bdr-offset-gradient-border *::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
}
}Customizing this snippet
- Color: set
--bdr-coloron the element or a parent. Currently previewing#3b82f6. - Base size: set
--bdr-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.