Border Draw Button
Two pseudo-elements draw the border around the button on hover: one grows along the top and right, the other along the bottom and left, meeting at the corners.
Also known as: animated border button, border trace hover.
HTML
<button class="hfx-border-draw">Explore</button>
CSS
.hfx-border-draw {
--c: var(--hfx-color, #3b82f6);
font-size: var(--hfx-size, 16px);
display: inline-flex;
align-items: center;
gap: 0.5em;
padding: 0.7em 1.6em;
border-radius: 0.5em;
font: 600 1em system-ui, sans-serif;
cursor: pointer;
position: relative;
border: 0;
border-radius: 0;
background: transparent;
color: var(--c);}
.hfx-border-draw::before,
.hfx-border-draw::after {
content: "";
position: absolute;
width: 0;
height: 0;
border: 0 solid var(--c);
/* hidden while idle: a zero-size box still paints a 2px corner dot */
opacity: 0;
transition: width 0.25s ease 0.25s, height 0.25s ease, opacity 0s 0.5s;
}
.hfx-border-draw::before {
top: 0;
left: 0;
border-top-width: 2px;
border-right-width: 2px;
}
.hfx-border-draw::after {
bottom: 0;
right: 0;
border-bottom-width: 2px;
border-left-width: 2px;
}
.hfx-border-draw:hover::before,
.hfx-border-draw:hover::after {
width: 100%;
height: 100%;
opacity: 1;
transition: width 0.25s ease, height 0.25s ease 0.25s, opacity 0s;
}
@media (prefers-reduced-motion: reduce) {
.hfx-border-draw, .hfx-border-draw *, .hfx-border-draw::before, .hfx-border-draw::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.