JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrap"></div>

CSS

div.wrap {
    height: 25px;
    width: 100%;
    border: 1px solid #2E2E2E;
    border-radius: 25px;
    background: linear-gradient(to top, #BDBDBD, #6E6E6E, #2E2E2E);
    position: relative;
}

.wrap::before {
    position: absolute;
    content: '';
    height: 25px;
    width: 90%;
    background-image: linear-gradient(to top, #58D3F7 0%, #00BFFF 20%, #0489B1 50%, #00BFFF 80%, #58D3F7 100%);
    border-top-left-radius: 25px;
    border-bottom-left-radius: 25px;
    box-shadow: 
        3px 0px 3px 0px #2E2E2E;
}