<img src="https://picsum.photos/id/1022/200/200" alt="a nighty sky">
img {
--c: #8A9B0F; /* the border color */
--b: 10px; /* the border thickness*/
--g: 5px; /* the gap on hover */
padding: calc(var(--g) + var(--b));
--_g: #0000 25%,var(--c) 0;
background:
conic-gradient(from 180deg at top var(--b) right var(--b),var(--_g))
var(--_i,200%) 0 /200% var(--_i,var(--b)) no-repeat,
conic-gradient( at bottom var(--b) left var(--b),var(--_g))
0 var(--_i,200%)/var(--_i,var(--b)) 200% no-repeat;
transition: .3s, background-position .3s .3s;
cursor: pointer;
}
img:hover {
--_i: 100%;
transition: .3s, background-size .3s .3s;
}
body {
background: #e8e9ba;
display: grid;
grid-gap: 40px;
height: 100vh;
margin: 0;
grid-auto-flow: column;
place-content: center;
}
This Pen doesn't use any external CSS resources.
This Pen doesn't use any external JavaScript resources.