<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<div class="box">
<br/><br/>my content<br/><br/>
<div class="colorgraph">
<br/><br/>my content<br/><br/>
</div>
</div>
<!--
https://stackoverflow.com/questions/38850419/how-to-create-multi-color-border-in-css3
https://bootsnipp.com/snippets/featured/simple-login-form-bootsnipp-style-colorgraph
-->
.colorgraph {
height: 7px;
border-top: 0;
background: #c4e17f;
border-radius: 5px;
background-image: -webkit-linear-gradient(left, #c4e17f, #c4e17f 12.5%, #f7fdca 12.5%, #f7fdca 25%, #fecf71 25%, #fecf71 37.5%, #f0776c 37.5%, #f0776c 50%, #db9dbe 50%, #db9dbe 62.5%, #c49cde 62.5%, #c49cde 75%, #669ae1 75%, #669ae1 87.5%, #62c2e4 87.5%, #62c2e4);
background-image: -moz-linear-gradient(left, #c4e17f, #c4e17f 12.5%, #f7fdca 12.5%, #f7fdca 25%, #fecf71 25%, #fecf71 37.5%, #f0776c 37.5%, #f0776c 50%, #db9dbe 50%, #db9dbe 62.5%, #c49cde 62.5%, #c49cde 75%, #669ae1 75%, #669ae1 87.5%, #62c2e4 87.5%, #62c2e4);
background-image: -o-linear-gradient(left, #c4e17f, #c4e17f 12.5%, #f7fdca 12.5%, #f7fdca 25%, #fecf71 25%, #fecf71 37.5%, #f0776c 37.5%, #f0776c 50%, #db9dbe 50%, #db9dbe 62.5%, #c49cde 62.5%, #c49cde 75%, #669ae1 75%, #669ae1 87.5%, #62c2e4 87.5%, #62c2e4);
background-image: linear-gradient(to right, #c4e17f, #c4e17f 12.5%, #f7fdca 12.5%, #f7fdca 25%, #fecf71 25%, #fecf71 37.5%, #f0776c 37.5%, #f0776c 50%, #db9dbe 50%, #db9dbe 62.5%, #c49cde 62.5%, #c49cde 75%, #669ae1 75%, #669ae1 87.5%, #62c2e4 87.5%, #62c2e4);
}
.fancy-border {
width: 150px;
height: 150px;
text-align:center;
border-top: 5px solid;
border-image: linear-gradient(to right, grey 25%, yellow 25%, yellow 50%,red 50%, red 75%, teal 75%) 5;
}
.box {
width: 350px;
height: 350px;
text-align:center;
}