.bordered-top {
border-image: linear-gradient(to right, rgb(139, 191, 64) 25%, rgb(230, 27, 33) 25%, rgb(230, 27, 33) 50%, rgb(124, 196, 236) 50%, rgb(124, 196, 236) 75%, rgb(254, 181, 17) 75%);
border-image-slice: 1;
border-image-width: 4px 0px 0px 0px;
}
.bordered-bottom {
border-image: linear-gradient(to right, rgb(139, 191, 64) 25%, rgb(230, 27, 33) 25%, rgb(230, 27, 33) 50%, rgb(124, 196, 236) 50%, rgb(124, 196, 236) 75%, rgb(254, 181, 17) 75%);
border-image-slice: 1;
border-image-width: 0px 0px 4px 0px;
}
.bordered-left {
border-image: linear-gradient(to bottom, rgb(139, 191, 64) 25%, rgb(230, 27, 33) 25%, rgb(230, 27, 33) 50%, rgb(124, 196, 236) 50%, rgb(124, 196, 236) 75%, rgb(254, 181, 17) 75%);
border-image-slice: 1;
border-image-width: 0px 0px 0px 4px;
}
.bordered-right {
border-image: linear-gradient(to bottom, rgb(139, 191, 64) 25%, rgb(230, 27, 33) 25%, rgb(230, 27, 33) 50%, rgb(124, 196, 236) 50%, rgb(124, 196, 236) 75%, rgb(254, 181, 17) 75%);
border-image-slice: 1;
border-image-width: 0px 4px 0px 0px;
}
div {
height: 100px;
width: 300px;
padding: 10px;
background: beige;
margin: 10px;
}
<!-- library added only for old browser support -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>
<div class='bordered-top'>Border only on top</div>
<div class='bordered-bottom'>Border only on bottom</div>
<div class='bordered-left'>Border only on left</div>
<div class='bordered-right'>Border only on right</div>